Methods and systems for mitigating denial of service (dos) attack in a wireless network

ABSTRACT

The present disclosure relates to a pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution. Methods and systems for mitigating Denial of Service (DOS) attacks in wireless networks, by performing admission control by verifying a User Equipment&#39;s (UE&#39;s) registration request via a Closed Access Group (CAG) cell without performing a primary authentication are provided. Embodiments herein disclose methods and system for verifying permissions of the UE to access a CAG cell based on the UE&#39;s Subscription identifier, before performing the primary authentication. The method for mitigating DOS attacks in wireless networks includes requesting a public land mobile network for accessing a non-public network (NPN) through a CAG cell, verifying the permissions of a UE to access the requested NPN through the CAG cell, and performing a primary authentication.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 17/806,654filed Jun. 13, 2022, now U.S. Pat. No. 11,706,626 issued Jul. 18, 2023,which is a continuation of application Ser. No. 16/803,828, now U.S.Pat. No. 11,363,463 issued Jun. 14, 2022, which is based on and derivesthe benefit of Indian Provisional Application 201941007734 filed on Feb.27, 2019 and Indian Complete Specification 201941007734, filed on Feb.25, 2020, the contents of which are incorporated herein by reference.

BACKGROUND 1. Field

The present disclosure relates to the field of wireless networks andmore particularly to mitigating Denial of Service (DoS) attacks inwireless networks.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4th generation (4G) communication systems, efforts havebeen made to develop an improved 5th generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud RadioAccess Networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, Coordinated Multi-Points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and slidingwindow superposition coding (SWSC) as an advanced coding modulation(ACM), and filter bank multi carrier (FBMC), non-orthogonal multipleaccess (NOMA), and sparse code multiple access (SCMA) as an advancedaccess technology have been developed.

Currently, private wireless networks/non-public networks (NPNs) aredeployed by enterprises to meet and optimize coverage, performance, andsecurity requirements of their business processes. The NPNs may bedeployed as non-stand-alone NPNs and stand-alone NPNs. Thenon-stand-alone NPNs are deployed in conjunction with Public Land MobileNetworks (PLMNs) using Closed Access Group (CAG) cell and/or networkslicing, also termed as Public Network integrated Non-Public Network.When the non-stand-alone NPNs are deployed with the PLMNs, UserEquipments (UEs) may access the NPNs and obtain services provided by theNPNs via the PLMNs using the CAG cells. The CAG identifies a group ofsubscribers/UEs, who are permitted to access one or more CAG cells/NPNs.The CAG may also prevent the UEs from automatically selecting andregistering from a location, which does not provide access to the NPNs,or from a location, which the UEs are not allowed to access the NPNs.The CAG is identified by a CAG identifier (CAG ID), which is broadcastedby the CAG cells/NPNs. The CAG cell broadcasts one or multiple CAGIdentifiers per PLMN. The UEs may have NPNpermissions/subscriptions/authorization to access the NPNs via the PLMN.The UEs may be further configured with an allowed list of CAG IDs/CAGcells (hereinafter referred as permissions to access the CAG cells/NPNs)based on its NPN permissions/subscriptions/authorization. When the UEswant to access the CAG cells/NPNs, the PLMN has to verify whether theUEs are allowed to access the CAG cells based on the NPNpermissions/subscriptions of the UEs and the allowed list of CAG cellsfor the UEs. Embodiments herein use the terms such as “permissions”,“subscription”, “authorization” and so on interchangeably.

The stand-alone NPNs may be deployed without requiring the support ofthe PLMNs. The stand-alone NPNs may use the CAG and/or a non-publicnetwork identifier to identify a group of subscribers/UEs, who arepermitted/authorized to access the one or more CAG cells/NPNs.

As per current 3GPP specification (TS 23.501), in order to access theNPNs, the UE initiates a registration procedure by sending asubscription concealed identifier (SUCI) in an initial Non AccessStratum (NAS) message (for example; a registration message) or in anyNAS message (for example; an identity response message) to a servingnetwork of the PLMN. The serving network performs a primaryauthentication procedure to authenticate the UE based on the receivedSUCI (after deconcealing the SUCI and deriving the SUPI) of the UE. Oncethe primary authentication is successful, the serving network verifiesif the UE has permissions or if the UE is authorized to access the CAGcells/NPN and enables the UE to access the CAG cells/NPNs based on asuccessful verification. However, the serving network has to wait untilcompletion of the successful primary authentication procedure to verify,if the UE has the permissions to access the CAG cells/NPN cells, whichmay result in an overhead on the serving network.

Further, when there are a large number of UEs in the network, theregistration procedures performed by rogue/malfunctioning/malicious UEsto access the NPNs in the particular CAG cell or distributed atdifferent CAG cells with/without having the valid NPN permissions andwithout having access to the CAG cells lead to (Distributed) Denial ofService ((D)DoS) attacks on the serving network.

The (D)DOS attacks may be possible when the UE performs the registrationprocedure with the valid NPN permissions and no permissions to the CAGcells or when the UE performs the registration procedure with no validNPN permissions and no permissions to access the CAG cells.

Consider an example scenario, wherein the UE may be connected to a NewRadio (NR/5G) network of the PLMN and the UE has the valid NPNpermissions and does not have the permissions to access the CAG cells.The 5G network includes a NG-Radio Access Network (RAN), and a 5G core(5GC) network/serving network. The 5GC includes elements such as, butnot limited to, an Access and Mobility Management Function (AMF), aUnified Data Management (UDM), an Authentication Server Function (AUSF),and so on.

In such a scenario, the UE initiates the registration procedure foraccessing/obtaining the services provided by the CAG cell/NPN. The UEinitiates the registration procedure by sending the SUCI as its identityto the NG-RAN requesting the access to the CAG cell/NPN. The NG-RANforwards the received SUCI along with the CAG ID of the requested CAGcell/NPN to the AMF. The AMF inserts the CAG ID in the SUCI and forwardsthe SUCI of the UE along with the CAG ID to the UDM. The UDM reveals thereceived SUCI and generates an authentication vector. Based on thegenerated authentication vector by the UDM, the AMF authenticates theUE. In an example herein, consider that the primary authenticationprocedure is successful, since the UE has the valid NPN permissions.Once the primary authentication procedure is successful, the AMFreceives a subscription permanent identifier (SUPI) of the UE from theAUSF and verifies if the UE has the permissions to access the requestedCAG cell/NPN based on the received SUPI. In an example herein, the AMFverifies that the UE is not authorized to access the CAG cells, sincethe UE does not have the permissions. Thereafter, the AMF rejects theregistration procedure initiated by the UE.

Consider another example scenario, wherein the UE is a rogue UE with novalid NPN permissions and no permissions to access the CAG cell/NPN. Insuch a scenario, the rogue UE sniffs the serving network and capturesthe SUCI (may or may not have the permissions to the CAG cell). Therogue UE then initiates the registration procedure by sending thecaptured SUCI as its identity to the AMF through the NG-RAN, wherein theNG-RAN may add the CAG ID of the requested CAG cell/NPN to the SUCI. TheAMF forwards the received SUCI along with the CAG ID to the UDM, whereinthe UDM reveals the SUCI, and generates the authentication vector. Basedon the generated authentication vector, the AMF performs theauthentication procedure. In an example herein, the AMF rejects theregistration procedure of the UE, since the authentication fails, as therogue UE does not have the valid NPN permissions.

Thus, in both the scenarios, irrespective of whether the UE possessesthe valid NPN permissions or not, the serving network has to perform theprimary authentication procedure to authorize the CAG cell access of theUE. Such procedures may lead to the overhead and the (D)DOS attacks onthe serving network.

The principal object of the embodiments herein is to disclose methodsand systems for mitigating (Distributed) Denial of Service ((D)DOS)attacks in a wireless network, wherein the wireless network includes atleast one non-public network (NPN) coupled with a Public Land MobileNetwork (PLMN).

Another object of the embodiments herein is to disclose methods andsystems for mitigating the (D)DoS attacks by verifying permissions of atleast one User Equipment (UE) to access the at least one NPN beforeperforming a primary authentication of the at least one UE.

Another object of the embodiments herein is to disclose methods andsystems for verifying the permissions of the at least one User Equipment(UE) to access the at least one NPN using a subscription permanentidentifier (SUPI) of the at least one UE and a Closed Access Group (CAG)Identifier (ID) of the requested at least one NPN.

SUMMARY

Accordingly, the embodiments herein provide methods and systems forcontrolling permissions of at least one User Equipment (UE) to access atleast one Non-Public Network (NPN) in a wireless network. A methoddisclosed herein includes requesting, by the at least one UE, a PublicLand Mobile Network (PLMN) for accessing the at least one NPN through atleast one Closed Access Group (CAG) cell. The method further includesverifying, by a Core Network (CN) of the PLMN, the permissions of the atleast one UE for accessing the requested at least one NPN through the atleast one CAG cell. The method further includes performing, by the CN, aprimary authentication procedure to allow the at least one UE foraccessing the at least one NPN through the at least one CAG cell, if thepermissions of the at least one UE for accessing the requested at leastone NPN through the at least one CAG cell are verified.

Accordingly, the embodiments herein disclose a network comprising atleast one User Equipment, at least one Non-Public network (NPN), and aPublic Land Mobile Network (PLMN), deployed in conjunction with the atleast one NPN. The PLMN includes at least one cellular networkcomprising of a Radio Access Network and a Core Network (CN). The atleast one UE is configured to request the PLMN for accessing the atleast one NPN through at least one Closed Access Group (CAG) cell. TheCN of the PLMN is configured to verify permissions of the at least oneUE for accessing the requested at least one NPN via the at least one CAGcell. The CN is further configured to perform a primary authenticationprocedure to allow the at least one UE for accessing the at least oneNPN through the at least one CAG cell, if the permissions of the atleast one UE for accessing the requested at least one NPN through the atleast one CAG cell are verified.

These and other aspects of the example embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingexample embodiments and numerous specific details thereof, are given byway of illustration and not of limitation. Many changes andmodifications may be made within the scope of the example embodimentsherein without departing from the spirit thereof, and the exampleembodiments herein include all such modifications.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document. Those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments herein are illustrated in the accompanying drawings,throughout which like reference letters indicate corresponding parts inthe various figures. The embodiments herein will be better understoodfrom the following description with reference to the drawings, in which:

FIGS. 1A-1C depict a wireless communication system/wireless network,according to embodiments as disclosed herein;

FIG. 2 depicts various elements of the wireless network 100 configuredfor mitigating a (Distributed) Denial of Service (D)DoS attack,according to embodiments as disclosed herein;

FIG. 3 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the UDM of the 5GC, according toembodiments as disclosed herein;

FIG. 4 is a sequence diagram depicting the verification of thepermissions of the UE to access the CAG cell at the UDM of the 5GC bydirectly communicating with the AMF/SEAF, according to embodiments asdisclosed herein;

FIG. 5 is a sequence diagram depicting the verification of thepermissions of the UE to access the CAG cell at the UDM by communicatingwith the AMF/SEAF over get request message and get response messages,according to embodiments as disclosed herein;

FIG. 6 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the UDM 206 and/or the AUSF of the5GC, according to embodiments as disclosed herein;

FIG. 7 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the AUSF of the 5GC, according toembodiments as disclosed herein;

FIG. 8 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the CAG server on receiving therequest from the UDM, according to embodiments as disclosed herein:

FIG. 9 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the CAG server on receiving the SUCIof the UE from the AMF/SEAF, according to embodiments as disclosedherein;

FIG. 10 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the CAG server on receiving the SUCIof the UE from the AUSF, according to embodiments as disclosed herein;

FIG. 11 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the AMF/SEAF, according toembodiments as disclosed herein;

FIG. 12 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the AMF/SEAF by communicating withthe UDM over the service interface provided by the UDM, according toembodiments as disclosed herein;

FIG. 13 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the CAG server by communicatingdirectly with the AMF/SEAF, according to embodiments as disclosedherein;

FIG. 14 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the UDM on receiving the SUPI of theUE from the AMF/SEAF, according to embodiments as disclosed herein; and

FIG. 15 is a flow diagram depicting a method for controlling thepermissions of the at least one UE to access the at least one NPN in thewireless network, according to embodiments as disclosed herein.

DETAILED DESCRIPTION

FIGS. 1A through 15 , discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The example embodiments herein and the various features and advantageousdetails thereof are explained more fully with reference to thenon-limiting embodiments that are illustrated in the accompanyingdrawings and detailed in the following description. Descriptions ofwell-known components and processing techniques are omitted so as to notunnecessarily obscure the embodiments herein. The description herein isintended merely to facilitate an understanding of ways in which theexample embodiments herein can be practiced and to further enable thoseof skill in the art to practice the example embodiments herein.Accordingly, this disclosure should not be construed as limiting thescope of the example embodiments herein.

Embodiments herein disclose methods and systems for mitigating(Distributed) Denial of Service ((D)DOS) attacks in a wireless network,wherein the wireless network system includes at least one non-publicnetwork (NPN) coupled with a Public Land Mobile Network (PLMN).

Embodiments herein disclose methods and systems for mitigating the(D)DoS attacks by performing admission control by verifying permissionsof at least one User Equipment (UE) to access the at least one NPNthrough a Closed Access Group (CAG) cell before performing a primaryauthentication of the at least one UE. The term “admission control forNPN” means verifying whether there are permissions or whether there isauthorization for the UE to access the CAG cell. In an embodiment, ifthe UE has the permissions or subscription or authorization foraccessing the NPN, then the corresponding CAG IDs of the NPN are listedin the UE's allowed CAG list. An Allowed CAG list is a list of CAGIdentifiers the UE is allowed to access the CAG cell.

Referring now to the drawings, and more particularly to FIGS. 1A through15 , where similar reference characters denote corresponding featuresconsistently throughout the figures, there are shown exampleembodiments.

FIGS. 1A-1C depict a wireless communication system/wireless network 100,according to embodiments as disclosed herein. The wireless network 100referred herein can be configured to mitigate a (Distributed) Denial ofService (D)DoS attack on a public network integrated non-publicnetworks, which is resulting from a large number of registrationrequests from users/UEs who are not allowed to access the non-publicnetworks.

The wireless network 100 includes a Public Land Mobile Network (PLMN)102 a, one or more non-public networks (NPNs) 102 b, and a plurality ofUEs 104.

The PLMN 102 a includes one or more different cellular networks such,as, but not limited to, a Long Term Evolution (LTE) network, an advancedLTE network, a New Radio (NR)/5G network, a Narrowband Internet ofThings (NB-IoT), or any other next generation networks. The PLMN 102 acan be operated by a mobile network operator (MNO). The PLMN 102 a canbe configured to provide communication services provided by the MNO tothe UEs 104 in a specific region. Examples of the communication servicescan be, but is not limited to, a streaming service (streaming ofmultimedia data such as audio, video, text and so on), a file downloadservice, a carousel service (a service for combining file downloadservice and streaming service), a television (TV) service, an InternetProtocol (LP) Multimedia Subsystem (IMS) service, a non-3GPP service(for example: firewalling or the like), and so on. Embodiments hereinuse the terms such as “PLMN”, “cellular network”, “public network”,“3GPP access network”, and so on interchangeably to refer to a networkthat provides the communication services to public use in a givenregion.

The NPN(s) 102 b can be configured to provide coverage and privateservices to the UEs 104 present within a location such as, but is notlimited to, an organization, an enterprise, a factory, a campus, a room,a floor, and so on. The private services can include services that aredefined by the premises. Examples of the private services can be, but isnot limited to, a streaming service (streaming of multimedia data suchas audio, video, text and so on), a file download service, and so on.

In an embodiment, the NPN 102 b can be deployed as a non-stand aloneNPN. The non-stand alone NPN 102 b can be deployed in conjunction withthe PLMN 102 a. The NPN 102 b can be deployed in conjunction with thePLMN 102 a using a network slicing and/or a Closed Access Group (CAG)cell (as specified in 3GPP TS 23.501). The network slicing providesdedicated data network names (DNNs) networks, or one or more networkslice instances that can make the NPN 102 b available to the UEs104 viathe PLMN 102 a. The CAG can be identified using a CAG identifier (CAGID) that is broadcasted by the NPN/CAG cell 102 b, wherein the CAG ID isunique with respect to a PLMN ID. The CAG may be used by the NPN 102 bto prevent users/UEs from automatically selecting and registering from alocation/region/area, which does not provide access to the NPNs for theUEs 104, or from the location, which the UEs 104 are not allowed toaccess the NPNs. Embodiments herein use the term “CAG Identifier” and“non-public network identifier” interchangeably. The CAG ID can meanCAG-ID and/or NPN-ID. Embodiments herein use the terms such as, but notlimited to, “NPN”, “private network”, “public network integrated NPN”,“non-3GPP access network”, “non-standalone NPN”, “CAG cells”, and so oninterchangeably to refer to a network that confines the communicationservices within boundaries of the defined premises for the UEs 104.

In an embodiment, the NPN 102 b can be a standalone NPN. The stand-aloneNPN 102 b may be deployed without the support of the PLMNs. Thestand-alone NPN 102 b may use the CAG and/or a non-public networkidentifier to identify a group of subscribers/UEs, who are permitted toaccess the one or more CAG cells/NPN. Embodiments herein are furtherexplained considering the non-standalone NPN 102 b, but the standaloneNPN can also be considered, where the entities in the PLMN core network102 a are hosted by the NPN core network 102 b.

The UE(s) 104 referred herein can be a user device that is capable ofsupporting the PLMN 102 a and the NPN 102 b. Examples of the UE 104 canbe, but is not limited to, a mobile phone, a smartphone, a tablet, aphablet, a personal digital assistant (PDA), a laptop, a computer, awearable computing device, a vehicle infotainment device, an Internet ofThings (IoT) device, a Virtual Reality (VR) device, a Wireless Fidelity(Wi-Fi) router, a USB dongle, a sensor, a robot, an auto-guided vehicle,and so on. The UE 104 can include one or more processors/CentralProcessing Units (CPUs), a memory, a transceiver, and so on, forperforming at least one intended function/operation.

The UE 104 can be configured to access the PLMN 102 a and/or the NPN 102b for obtaining the communication services and/or the private services.In an embodiment, the UE 104 can access the PLMN 102 a via the NPN 102b. In an embodiment, the UE 104 can access the NPN and obtain theprivate network services provided by the NPN 102 b by havingsubscriptions to the PLMN. The UE's subscription to PLMN may include atleast one of NPN permissions/subscriptions and permissions/subscriptionsto access the CAG cell(s)/NPN(s) 102 b. The NPN permissions may indicatethat the UE 104 is authorized to access the NPN/the services provided bythe NPN 102 b via the PLMN 102 a. The permissions to access the CAGcell/NPN 102 b can indicate an allowed list of CAG cells/CAG IDs for theUE 104. The permissions to access the CAG cells can be configured forthe UE 104 based on its NPN permissions. The permissions to access theCAG cells/allowed CAG list is configured for the UE 104 using existing3GPP procedures (for example: over the air mechanism, UE configurationupdate procedure, or the like). Embodiments herein use the terms such as“permissions to access the CAG cell”, “CAG cell permissions”, “allowedlist of CAG cells/CAG IDs”, “allowed CAG cells permissions” and so oninterchangeably.

The UE 104 initiates a registration procedure when the UE 104 wants theaccess to the CAG cell/NPN 102 b or to the services provided by the NPN102 b. The UE 104 sends a registration request to the PLMN 102 a byrequesting access to the CAG cell/NPN 102 b. In an example herein, therequested PLMN 102 a can be a home PLMN (HLPMN), with which the UE 104has already subscribed. In an embodiment, on receiving the registrationrequest from the UE 104, the PLMN 102 a verifies if the UE 104 has thepermissions (or if the UE 104 is authorized) to access the requested CAGcell/NPN 102 b. On verifying that the UE 104 is authorized/or the UE 104has the permissions to access the requested CAG cell/NPN 102 a, the PLMN102 a performs a primary authentication procedure to check if the UE 104is an authenticated UE 104. Based on the successful authentication, thePLMN proceeds further with UE's registration request procedure for UE'saccess to the NPN.

On verifying that the UE 104 does not have the permissions (or the UE104 is not authorized) to access the requested CAG cell/NPN 102 b, thePLMN 102 a rejects the registration request of the UE 104 and does notenable the UE 104 to access the requested CAG cell/NPN 102 b. Thus,verifying by the PLMN 102 a the permissions/authorization of the UE 104to access the NPN 102 b before performing the primary authenticationprocedure mitigates the (D)DoS attack on the PLMN 102 a, which isresulting from the registration procedure initiated by the UE 104 withno valid permissions to access the CAG cell/NPN 102 b.

As depicted in FIG. 1 b , the NPN 102 b includes a non-public RadioAccess Network (RAN) 106 b, and a non-public Core Network (CN) 108 b.The non-public RAN 106 b referred herein can be 3GPP access nodes,non-3GPP access nodes, and so on. Examples of the 3GPP access nodes canbe, but not limited to, evolved nodes (eNBs), New Radio nodes (gNBs),and so on. Examples of the non-3GPP access nodes can be, but is notlimited to, a Local Access Network (LAN) node, a Wireless LAN (WLAN)node, a Wi-Fi node, and so on. The non-public RAN 106 b of the NPN 102 bcan be a RAN of the PLMN 102 a including an assistance of the CAG cell.The PLMN 102 a hosts the RAN 106 b to access the NPN 102 b. Thenon-public RAN 106 b can be configured to connect the at least one UE104 to the non-public CN 108 b. The non-public CN 108 b can beconfigured to connect the UE 104 to the external data network/PLMN 102a. The non-public CN 108 b can be at least one of an EPC network, a 5GCcore network, and so on. In an embodiment, the NPN 102 b can share thenon-public RAN 106 b with the PLMN 102 a. The NPN 102 b and the PLMN 102a can include different identifiers (IDs), segregated spectrum bands,and functionalities of the CNs (for example, user plane and data planefunctionalities of the CNs). In an embodiment, the NPN 102 b canpartially share the non-public RAN 106 b with the PLMN 102 a, so thatone or more of the functions of the non-public RAN 106 b serving the NPN102 b can be provided by the PLMN 102 a. In an embodiment, the NPN 102 bcan share the non-public RAN 106 b and the spectrum bands with the PLMN102 a. In an embodiment, the NPN 102 b can share the non-public RAN 106b and the control plane functionalities of the non-public CN 108 b withthe PLMN 102 a.

The PLMN 102 a includes at least one cellular network 106 comprising ofat least one RAN 106 a, and a CN 108 a. The RAN 106 a can be configuredto connect the at least one UE 104 to the CN 108 a. The RAN 106 a maycomprise of nodes/Base Stations (BSs) such as, but not limited to,evolved nodes (eNBs), New Radio nodes (gNBs), and so on. The RAN 106 amay comprise of or more processors/Central Processing Units (CPUs), amemory, a transceiver, and so on, for performing at least one intendedfunction/operation.

The CN 108 a referred herein can be at least one of an Evolved PacketCore (EPC), a 5G core (5GC) network, or the like. The CN 108 a can beconnected to the RAN 106 a and an external data network. Examples of theexternal data network can be, but not limited to, the Internet, a PacketData Network (PDN), an Internet Protocol (IP) Multimedia Core NetworkSubsystem, and so on. In an embodiment, the CN 108 a can be connected tothe non-public CN 108 b over the N3IWF interface. Embodiments herein usethe terms such as “core network (CN)”, “serving network”, and so oninterchangeably.

The CN 108 a may comprise of one or more processors/Central ProcessingUnits (CPUs), a memory, a storage, a transceiver, and so on, forperforming at least one intended function/operation. The CN 108 a can beconfigured to maintain information about at least one of NPN permissionsof the UE 104, a subscription permanent identifier (SUPI) of the UE 104,and the allowed list of CAG cells/CAG IDs configured for the UE 104, amapping of the allowed list of CAG cells with the SUPI of the UE 104,and so on. The allowed list of CAG cells can be configured for the UE104 based on the valid NPN permissions of the UE 104. The allowed listof CAG cells may include information about the CAG IDs of the CAGcells/NPNs 102 b, which the UE 104 can access. The SUPI can be a uniqueidentifier that is allocated to the UE 104 by the MNO during a UniversalSubscriber Identity Module (USIM) registration process performed by theUE 104 to register with the network system 100. The SUPI can be eitheran International Mobile Subscriber Identifier (IMSI) (as specified in TS23.503) or a Network Access Identifier (NAI) (as specified in TS23.0003), and so on.

The CN 108 a can be configured to connect the at least one UE 104(connected with the at least one RAN node 106 a) to an external datanetwork. The CN 108 a can also be configured to enable the UE(s) 104 toaccess the NPN 102 b. In an embodiment, the CN 108 a can enable theUE(s) 104 to access the NPN 102 b by verifying the permissions of the UE104 to access the NPN 102 b before performing the primary authenticationprocedure, thereby mitigating the (D)DoS attack and minimizing theoverhead on the PLMN 102 a.

As depicted in FIG. 1 b , for accessing the NPN 102 b or obtaining theservices provided by the NPN 102 b, the UE 104 performs the registrationprocedure with the CN 108 a of the PLMN 102 a. The UE 104 performs theregistration procedure by sending the registration request to theconnected RAN 106 a of the PLMN 102 a requesting the access to the NPN102 b or to the services provided by the NPN 102 b. The registrationrequest includes a subscribed concealed identifier (SUCI) of the UE 104.The SUCI can be a privacy preserving identifier containing a concealedSUPI. In an example, the UE 104 may generate the SUCI using an EllipticCurve Integrated Encryption Scheme (ECIES)-based protection scheme witha public key of the home network/HPLMN 102 a that was securelyprovisioned to the UE 104 during the USIM registration. The UE 104 cansend the registration request including the SUCI to the NG-RAN 106 a inan initial Non-Access Stratum (NAS) message, or any NAS message (forexample, Identity Response message, or the like).

On receiving the SUCI from the UE 104, the RAN 106 a identifies the CAGID of the requested CAG cell/NPN 102 b (based on the broadcast of theCAG IDs by the CAG cells/NPNs 102 b). The RAN 106 a forwards thereceived SUCI of the UE 104 and the identified CAG ID of the requestedCAG cell/NPN 102 b to the CN 108 a. In an embodiment, the RAN 106 a mayalso receive the CAG ID of the requested CAG cell/NPN 102 b from the UE104.

On receiving the SUCI of the UE 104 and the CAG ID of the requested CAGcell/NPN 102 b, the CN 108 a verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b before performing the primaryauthentication procedure. For verifying the permissions, the CN 108 areveals the received SUCI to the SUPI (as specified in 3GPP TS. 23.501).The CN 108 a retrieves the allowed list of CAG cells/CAG IDs for the UE104 based on the revealed SUPI. The CN 108 a uses the maintained mappingof the allowed list of CAG cells with the SUPI of the UEs 104 andretrieves the allowed list of CAG cells for the revealed SUPI. The CN108 a checks if the received CAG ID of the requested CAG cell/NPN 102 ais present in the retrieved allowed list of cells/CAG IDs for the UE104.

On checking that the received CAG ID of the requested CAG cell/NPN 102 ais present in the retrieved allowed list of cells/CAG IDs for the UE104, the CN 108 a verifies that the UE 104 has the permission to accessthe CAG cell/NPN 102 b (a successful verification). Thereafter, the CN108 a performs the primary authentication procedure to authenticate ifthe UE 104 has the valid NPN permissions to access the requested NPN 102b via the PLMN 102 a. For performing the primary authenticationprocedure, the CN 108 a generates an authentication vector based on thereceived SUCI (as specified in 3GPP TS 23.501) and authenticates the UE104 based on the generated authentication vector. Once theauthentication procedure is successful, the CN 108 a enables the UE 104to access the requested CAG cell/NPN 102 b by performing a procedure asspecified in 3GPP TS 23.501.

On checking that the received CAG ID of the requested CAG cell/NPN 102 ais not present in the retrieved allowed list of cells/CAG IDs for the UE104, the CN 108 a verifies that the UE 104 does not have the permissionsto access the CAG cell/NPN 102 b (an unsuccessful verification). The CN108 a then rejects the registration request of the UE 104 withoutproceeding with the primary authentication procedure. On rejecting theregistration request, the CN 108 a sends a reject message to the UE 104through the RAN 106 a indicating that the requested CAG cell/NPN 102 baccess is not allowed. The CN 108 a also sends an appropriate causevalue along with the reject message to the UE 104. The cause value canbe a value depicting a cause of an error due to which the UE 104 cannotaccess the requested CAG cell/NPN 102 b or the services provided by therequested CAG cell/NPN 102 b at a present location. Examples of thecause value can be, but not limited to, #12, #13 , #15 , #76, and so on.In an example, the cause value #15 indicates that there are no suitableCAG cells in a location/tracking area (wherein the UE 104 is present) ofthe HPLMN 102 a or the CAG cells access is not allowed for the UE 104.In an example, the cause value #12 indicates that the CAG cell access inthe requested tracking area is not allowed. In an example, the causevalue #13 indicates that roaming is not allowed for the requestedtracking area.

Thus, verifying the permissions of the UE 104 to access the CAG cellbefore performing the primary authentication procedure mitigates the(D)DoS on the CN 108 a and reduces overheads on the CN 108 a forperforming the primary authentication procedure.

In an embodiment, the PLMN 102 a may deploy a CAG server 110, which cancommunicate with the CN 108 a of the at least one cellular network 106as depicted in FIG. 1 c . The CAG server 110 can perform at least oneintended function of the CN 108 a. The CAG server 110 can maintaininformation about at least one of NPN permissions of the UE 104, theSUPI of the UE 104, and the allowed list of CAG cells/CAG IDs configuredfor the UE 104, the mapping of the allowed list of CAG cells with theSUPI of the UE 104, and so on. The CAG server 110 can verify thepermissions of the UE 104 to access the NPN 102 b before performing theprimary authentication procedure.

FIG. 2 is a block diagram depicting various elements of the wirelessnetwork 100 configured for mitigating the (D)DoS attack, according toembodiments as disclosed herein. Embodiments herein are furtherexplained by considering that the PLMN 102 a includes a 5G network 106as the cellular network 106 and the non-public CN 108 b as the 5GC 108 bas examples, but any other cellular network and any other CN can beconsidered.

As depicted in the example in FIG. 2 , the RAN 106 a of the 5Gnetwork/PLMN 102 a can be the NG-RAN/gNB 106 a and the CN 108 a can bethe 5GC 108 a. The 5GC 108 a includes an access and mobility managementfunction (AMF)/security anchor function (SEAF) 202, an authenticationserver function (AUSF) 204, and a unified data management (UDM)/anauthentication credential Repository (ARPF)/subscription identifierrevealing function 206. The CN 108 a also includes other elements suchas, but not limited to, a session management function (SMF), a userplane functionality (UPF), a policy control function, an applicationfunction, a network exposure function (NEF), a NF repository function(NRF), a network slice selection function (NSSF), and so on (not shown).In an embodiment, the CAG server 110 can communicate with the elementsof the 5GC 108 a over a service interface exhibited by the CAG server110. In an example, the service interface can be a Ncag_XXX interface.Similarly, the non-public CN 108 b/non-public 5GC 108 a includes all theelements of the 5GC 108 a (not shown).

In an embodiment, if the SEAF and the AMF 202 are not co-located, thenthe AMF 202 connects to the AUSF 204 via the SEAF. In an embodimentherein, if the SEAF and the AMF are co-located, then the term “AMF”means “AMF/SEAF” 202 throughout this document.

The AMF/SEAF 202 can be configured to support functions such as, but notlimited to, termination of NAS signaling, NAS ciphering and integrityprotection, registration management, connection management, mobilitymanagement, access authentication and authorization, security contextmanagement, and so on. The AUSF 204 can be an authentication serverconfigured to authenticate the UEs 104 by maintaining information aboutthe UEs 104.

The UDM/ARPF/SIDF 206 can be configured to perform functions such as,but not limited to, generation of authentication and key agreement (AKA)credentials, user identification handling, access authorization,subscription management, and so on. In an embodiment herein, the UDM,the ARPF, and the SIDF may or may not operate mutually to perform the atleast one function.

Embodiments herein enable at least one of the UDM 206, the UDM/ARPF/SIDF206, the AUSF 204, the AMF/SEAF 202, and the CAG server 110 to verify ifthe UE 104 is authorized (or the UE has the permissions) to access theCAG cell/NPN 102 b before performing the primary authenticationprocedure.

Embodiments herein enable the UDM 206 of the 5GC 108 a to verify thepermissions of the UE 104 to access the CAG cells/NPN 102 b. As a partof the registration procedure, for accessing the CAG cell/NPN 102 b, theUE 104 sends the registration request including the SUCI to the NG-RAN106 a. In an embodiment, the UE 104 may send the registration request tothe NG-RAN 106 a in the initial NAS message. In an embodiment, the UE104 may send the registration request to the NG-RAN 106 a in a NASmessage (for example, in an Identity Response Message). The NG-RAN 106 aforwards the received SUCI of the UE 104 to the AMF/SEAF 202. In anembodiment, the NG-RAN 106 a identifies the CAG ID broadcasted by therequested CAG cells/NPN 102 b and adds the CAG ID to the SUCI forsending to the AMF/SEAF 202 over an N2 message. In an embodiment, theNG-RAN 106 a receives the CAG ID (that is broadcasted by the requestedCAG cell/NPN 102 a) along with the SUCI from the UE 104. In such a case,the NG-RAN 106 a forwards the SUCI along with the CAG ID to the AMF/SEAF202.

The AMF/SEAF 202 includes the received SUCI of the UE 104, the CAG ID ofthe requested CAG cell/NPN 102 b, other parameters in an authenticationrequest message (Nausf_UEAuthentication_Authenticate request message)and sends the authentication request message to the AUSF 204. Examplesof the other parameters can be, but not limited to, a SN name, or thelike. The AUSF 204 derives the SUCI of the UE 104, the CAG ID of therequested CAG cell/NPN 102 b, and the other parameters from the receivedauthentication request message. The AUSF 204 inserts the derived SUCI ofthe UE 104, the CAG ID of the requested CAG cell/NPN 102 b, and theother parameters in an authentication get request message(Nudm_UEAuthentication_Get_Request message). The AUSF 204 sends theauthentication get request message to the UDM 206 of the 5GC 108 a.

On receiving the authentication get request message, the UDM 206 checksif the CAG ID is present in the received message. If the CAG ID ispresent in the received message, the UDM 206 verifies the permissions ofthe UE 104 to access the requested CAG cell/NPN 102 b before performingthe primary authentication procedure. For verifying the permissions, theUDM 206 reveals the received SUCI to the SUPI (as specified in 3GPP TS23.501). The UDM 206 retrieves the allowed list of CAG cells/CAG LDs forthe UE 104 based on the revealed SUPI. The UDM 206 uses the maintainedmapping of the allowed list of CAG cells with the SUPI of the UEs 104 toretrieve the allowed list of CAG cells for the revealed SUPI. The UDM206 checks if the received CAG ID of the requested CAG cell/NPN 102 a ispresent in the retrieved allowed list of cells/CAG IDs for the UE 104.

On checking that the received CAG ID of the requested CAG cell/NPN 102 ais present in the retrieved allowed list of cells/CAG IDs for the UE104, the UDM 206 verifies that the UE 104 has the permissions to accessthe CAG cell/NPN 102 b. On verifying that the UE 104 has the permissionsto access the CAG cell, the UDM 206 selects an authentication method,and generates the authentication vector (following procedures specifiedin 3GPP TS 23.501). The UDM 206 sends the generated authenticationvector to the AMF/SEAF 202 through the AUSF 204 to perform the primaryauthentication procedure. On receiving the authentication vector fromthe UDM 206, the AMF/SEAF 202 authenticates the UE 104 and enables theUE 104 to access the NPN 102 b on the successful authentication.

If the received CAG ID of the requested CAG cell/NPN 102 a is notpresent in the retrieved allowed list of cells/CAG IDs for the UE 104,the UDM 206 verifies that the UE 104 does not have the permissions toaccess the CAG cell/NPN 102 b. After verifying that the UE 104 does nothave the permissions to access the CAG cell/NPN 102 b, the UDM 206 doesnot proceed with the primary authentication procedure. The UDM 206inserts the SUPI, and a CAG cell reject message in a get responsemessage (Nudm_UEAuthentication_Get Response message) and sends the getresponse message to the AUSF 204.

On receiving the response message including the CAG cell reject message,the AUSF 204 includes the received CAG cell reject message in anauthentication response message (Nausf_UEAUthentication_Authenticateresponse message) and forwards the authentication response message tothe AMF/SEAF 202.

On receiving the authentication response message including the CAG cellreject message from the AUSF 204, the AMF/SEAF 202 rejects the receivedregistration request of the UE 104. The AMF/SEAF 202 sends aregistration reject message with the appropriate cause value to the UE104. The cause value indicates that the UE 104 cannot access therequested CAG cell/NPN 102 b or the services provided by the requestedCAG cell/NPN 102 b.

By performing the check at the UDM 206, the (D)DoS attack on the networkis minimized without reducing the level of the 5GS security, that is notrevealing the SUPI to the AMF 202 before the primary authentication tomaintain the user privacy, but performing the authorization efficientlyand not providing any information to the UE 104 other than causevalue/error cause.

Embodiments herein enable the UDM 206 and/or the AUSF 204 to verify thepermissions of the UE 104 to access the CAG cells/NPN 102 b. Foraccessing the CAG cells/NPN 102 b or the services provided by the NPN102 b, the UE 104 sends the registration request along with the SUCI tothe NG-RAN 106 a. The NG-RAN 106 forwards the received SUCI of the UE104 to the AMF/SEAF 202. The AMF/SEAF 202 may receive the SUCI from theNG-RAN 106 and the CAG cell ID either from the NG-RAN 106 a or from theUE 104 in the registration request message. The AMF/SEAF 202 includesthe received SUCI of the UE 104, the CAG ID of the requested CAGcell/NPN 102 b, and the other parameters in at least one of a Nausf_XXXRequest message and a Nausf_UEAuthentication_Authenticate Requestmessage. The AMF/SEAF 202 sends at least one of the Nausf_XXX Requestmessage, and the Nausf_UEAuthentication_Authenticate Request message tothe AUSF 204.

The AUSF 204 includes the received SUCI of the UE 104, the CAG ID of therequested CAG cell/NPN 102 b, and the other parameters in at least oneof the Nudm_XXX Request message and the Nudm_UEAuthentication GetRequest message for sending to the UDM 206.

In an embodiment, on receiving the registration request messageincluding the SUCI and the CAG ID from the AUSF 204, the UDM 206 revealsthe SUCI to the SUPI (as per the 3GPP TS 33.501) and derives the allowedlist of the CAG cells for the UE 104 based on the SUPI. The UDM 206verifies if the UE 104 has the permissions to the requested CAG cell/NPN102 b based on the allowed list of the CAG cells for the UE 104 and thereceived CAG ID of the requested CAG cell/NPN 102 b. On verifying thatthe UE 104 has the permissions to the requested CAG cell/NPN 102 b, theUDM 206 sends the accept message to the AUSF 204 in at least one of theNudm_XXX Response message and the Nudm_UEAuthentication Get Responsemessage. The AUSF 204 further forwards the accept message to theAMF/SEAF 202 in at least one of the Nausf_XXX Response message and theNausf_UEAuthentication_Authenticate Response message. The AMF/SEAF 202may further perform the primary authentication procedure to authenticatethe UE 104 for accessing the CAG cell/NPN 102 b.

On verifying that the UE 104 does not have the permissions to therequested CAG cell/NPN 102 b, the UDM 206 sends the CAG cell rejectmessage along with the SUPI of the UE 104 to the AUSF 204 in at leastone of the Nausf_XXX Response message and theNausf_UEAuthentication_Authenticate Response message. The AUSF 204forwards the received CAG cell reject message to the AMF/SEAF 202 in atleast one of the Nausf_XXX Response message and theNausf_UEAuthentication_Authenticate Response message. The AMF/SEAF 202rejects the registration request message of the UE 104 with theappropriate cause value.

In an embodiment, on receiving the registration request messageincluding the SUCI and the CAG ID from the AUSF 204, the UDM 206 revealsthe SUCI to the SUPI and derives the allowed list of the CAG cells forthe UE 104 based on the SUPI. The UDM 206 may further send the allowedlist of CAG cells for the UE 104 to the AUSF 204 in at least one of theNausf_XXX Response message and the Nausf_UEAuthentication_AuthenticateResponse message for verifying the permissions of the UE 104. Based onthe received allowed list of CAG cells from the UDM 206 and the receivedCAG ID of the requested CAG cell from the AMF/SEAF 202, the AUSF 204verifies if the UE 104 has the permissions to access the requested CAGcells/NPN 102 b. On verifying that the UE 104 has the permissions toaccess the requested CAG cells/NPN 102 b, the AUSF 204 forwards theaccept message to the AMF/SEAF 202 in at least one of the Nausf_XXXResponse message and the Nausf_UEAuthentication_Authenticate Responsemessage. The AMF/SEAF 202 may further perform the primary authenticationprocedure to authenticate the UE 104 for accessing the CAG cell/NPN 102b.

On verifying that the UE 104 does not have the permissions to therequested CAG cell/NPN 102 b or if the AUSF 204 does not receive theallowed list of CAG cells from the UDM 206, the AUSF 204 sends the CAGcell reject message to the AMF/SEAF 202. The AUSF 204 may send the CAGcell reject message to the AMF/SEAF 202 in at least one of the Nausf_XXXResponse message and the Nausf_UEAuthentication_Authenticate Responsemessage. The AMF/SEAF 202 then rejects the registration request messageof the UE 104 with the appropriate cause value.

Embodiments herein enable the UDM 206 of the 5GC 108 a to verify thepermissions of the UE 104 to access the CAG cells/NPN 102 b bycommunicating directly with the AMF/SEAF 202. For accessing the CAGcells/NPN 102 b or the services provided by the NPN 102 b, the UE 104sends the registration request along with the SUCI to the NG-RAN 106 a.The NG-RAN 106 a forwards the received SUCI of the UE 104 to theAMF/SEAF 202. The AMF/SEAF 202 may receive the SUCI from the NG-RAN 106a and the CAG cell ID either from the NG-RAN 106 a or from the UE 104 inthe registration request message. The AMF/SEAF 202 directly requests theUDM 206 to verify if the UE 104 has the permissions to access the CAGcells/NPN 102 b. In an embodiment, the AMF/SEAF 202 may directly requestthe UDM 206 to verify the permissions of the UE 104 over serviceinterfaces provided by the UDM 206 such as, but not limited to, aNudm_XXX over Nudm interface, an N8 interface,Nudm_UEVerifyCAGAccess_Get, and so on. The AMF/SEAF 202 includes thereceived SUCI of the UE 104, the CAG ID of the requested CAG cell/NPN102 b, and the other parameters in at least one of a Nudm_XXX Requestmessage, a Nudm_UEVerifyCAGAccess_Get Request message and sends themessage to the UDM 206.

In response to requesting by the AMF/SEAF 202, the UDM 206 reveals thereceived SUCI to the SUPI and retrieves the allowed list of CAG cellsfor the UE 104 based on the revealed SUPI. The UDM 206 verifies if theUE 104 has the permissions to access the CAG cells/NPN 102 b using theallowed list of CAG cells for the UE 104 and the received CAG ID of therequested CAG cell/NPN 102 b. On verifying that the UE 104 has thepermissions to access the CAG cell/NPN 102 b, the UDM 206 may send anaccept message to the AMF/SEAF 202, which may further perform theprimary authentication procedure to authenticate the UE 104 foraccessing the CAG cell/NPN 102 b. The UDM 206 may send the acceptmessage to the AMF/SEAF 202 in at least one of a Nudm_XXX Responsemessage, and a Nudm_UEVerifyCAGAccess_Get Response message.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the UDM 206 may send a reject message to theAMF/SEAF 202 indicating that the UE 104 does not have the permissions toaccess to the CAG cell/NPN 102 b. The UDM 206 may send the rejectmessage to the AMF/SEAF 202 in at least one of the Nudm_XXX Responsemessage, and the Nudm_UEVerifyCAGAccess_Get Response message. Onreceiving the reject message from the UDM 206, the AMF/SEAF 202 rejectsthe registration request of the UE 104 and sends the reject messagealong with the appropriate cause value to the UE 104.

Embodiments herein enable the UDM to verify the permissions of the UE104 to access the CAG cells/NPN 102 b on receiving the SUPI from theAMF/SEAF 202 on receiving the SUPI from the AMF/SEAF 202. In anembodiment, the UE 104 initiates the service request procedure foraccessing the CAG cells/NPN 102 b by sending the service request messageto the AMF/SEAF 202 through the NG-RAN 106 a. In an embodiment, the UE104 can initiate the request procedure for accessing the CAG cells/NPN102 b by sending the registration request message including the SUCI ofthe UE 104 to the AMF/SEAF 202 through the NG-RAN 106 a, when theAMF/SEAF 202 may not be able to reveal the SUPI of the UE 104. TheAMF/SEAF 202 may receive the CAG ID of the requested CAG cell/NPN 102 beither from the NG-RAN 106 a or from the UE 104 in the service requestmessage. On receiving the service request of the UE 104, the AMF/SEAF202 may reveal the SUPI (for example: from UE's 5G-GUTI or the like so)of the UE 104. If the AMF/SEAF 202 does not have the information (theallowed list of CAG cells for the UE 104) to verify the permissions ofthe UE 104 to access the CAG cell, the AMF/SEAF 202 provides the SUPI ofthe UE 104 and the CAG ID of the requested CAG cell to the UDM 206 overthe Nudm_XXX message. The UDM 206 performs the verification of the UE'spermissions to the CAG cell. If the UDM 206 is unable to verify the UE'spermissions to access the CAG cell, the AMF/SEAF 202 sends the NASReject message with the appropriate cause value to the UE 104. If theUDM 206 is able to verify the UE's permissions to access the CAG cell,the AMF/SEAF 202 shall proceed further with the NAS/N2 procedure(Registration Request procedure or Path Switch Procedure or N2 HOprocedure).

Embodiments herein enable the AMF 202 to verify the permissions of theUE 104 to access the CAG cells/NPN 102 b. The UE 104 initiates theregistration procedure for accessing the CAG cells/NPN 102 b by sendingthe registration request message including the SUCI to the AMF 202through the NG-RAN 106 a. The AMF 202 may receive the CAG ID of therequested CAG cell/NPN 102 b either from the NG-RAN 106 a or from the UE104 in the registration request message. The AMF/SEAF 202 requests theUDM 206 for the SUPI and the allowed list of CAG cells by forwarding theSUCI of the UE 104 to the UDM 206. In an embodiment, the AMF/SEAF 202may forward the SUCI of the UE 104 to the UDM 206 in at least one of theNudm_XXX Request message, and a Nudm_SDM_Get Request message.

On receiving the SUCI of the UE 104 from the AMF/SEAF 202, the UDM 206reveals the SUCI of the UE 104 to the SUPI and retrieves the allowedlist of CAG cells for the UE 104 based on the revealed SUPI. In anembodiment, the UDM may send the SUPI of the UE 104 and the allowed listof CAG cells for the UE 104 to the AMF/SEAF 202 in at least one of theNudm_XXX Response message, and a Nudm_SDM_Get Response message

On receiving the allowed list of CAG cells for the UE 104 from the UDM206, the AMF/SEAF 202 verifies if the CAG ID of the requested CAG cellis present in the allowed list of CAG cells. If the CAG ID of therequested CAG cell is present in the allowed list, the AMF/SEAF 202determines that the UE 104 has the permissions to the CAG cell/NPN 102b, and proceeds further with the primary authentication procedure toauthenticate the UE 104 for accessing the NPN 102 b. If the CAG ID ofthe requested CAG cell is not present in the allowed list or if theAMF/SEAF 202 does not receive the allowed list from the UDM 206, theAMF/SEAF 202 determines that the UE does not have the permissions to theCAG cell/NPN 102 b. Thereafter, the AMF/SEAF 202 rejects theregistration request of the UE 104 with the appropriate cause value.

Embodiments herein enable the CAG server 110 to verify the permissionsof the UE 104 to access the CAG cell/NPN 102 a on receiving a requestfrom the UDM 206. The UDM 206 receives the registration request messageof the UE 104 including the SUCI of the UE 104 and the CAG ID from theAMF/SEAF 202 or the AUSF 204. The UDM 206 checks if the CAG ID isincluded in the registration request message. If the CAG ID is includedin the registration request message, the UDM 206 reveals the SUCI of theUE 104 to the SUPI. The UDM 206 forwards the SUPI of the UE 104 and theCAG ID of the requested CAG cell/NPN 102 b to the CAG server 110 over aservice based interface provided by the CAG server 110. In an example,the service based interface can be a Ncag_XXX, or the like. The CAGserver 110 retrieves the allowed list of CAG cells for the UE 104 basedon the received SUPI from the UDM 206. Based on the retrieved allowedlist of CAG cells and the CAG ID of the requested CAG cell, the CAGserver 110 verifies if the UE 104 has the permissions to access therequested CAG cell. The CAG server 110 sends the result (accept/reject)of the verification to the UDM 206. Based on the response from the CAGserver 110, the UDM 206 may proceed further with the registrationrequest of the UE 104 or reject the registration request of the UE 104.

Embodiments herein enable the CAG server 110 to verify the permissionsof the UE 104 to access the CAG cell/NPN 102 a on receiving a requestfrom the AMF/SEAF 202. The CAG server 110 receives the registrationrequest of the UE 104 from the AMF/SEAF 202, wherein the registrationrequest includes the SUCI of the UE 104 and the CAG ID of the requestedCAG cell/NPN 102 b. On receiving the registration request of the UE 104,the CAG server 110 forwards the SUCI of the UE 104 to the UDM 206 byrequesting for the SUPI of the UE 104. The CAG server 110 may forwardthe SUCI of the UE 104 to the UDM 206 in the Nudm_XXX message.

On receiving the NUdm_XXX request message, the UDM 206 reveals theobtained SUCI to the SUPI. The UDM 206 provides the SUPI of the UE 104to the CAG server in the Nudm_XXX Response message. On receiving theSUPI from the UDM 206, the CAG server 110 retrieves the allowed list ofCAG cells for the UE 104. Based on the retrieved allowed list of CAGcells and the CAG ID of the requested CAG cell, the CAG server 110verifies if the UE 104 has the permissions to access the requested CAGcell. The CAG server 110 sends the result (accept/reject) of theverification to the AMF/SEAF 202. Based on the response from the CAGserver 110, the AMF/SEAF 202 may proceed further with the registrationrequest of the UE 104 or reject the registration request of the UE 104.

Embodiments herein enable the CAG server 110 to verify if the UE 104 hasthe permissions to access to the CAG cells/NPN 102 b on receiving arequest from the AUSF 204. The AMF/SEAF 202 receives the registrationrequest of the UE 104 through the NG-RAN 106 a, wherein the registrationrequest may include the SUCI of the UE 104, and the CAG ID of therequested CAG cell/NPN 102 b. The AMF/SEAF 202 includes the SUCI of theUE 104, the CAG ID of the requested CAG cell, and the other parametersin the Nausf_XXX Request message and sends the Nausf_XXX Request messageto the AUSF 204. The AUSF 204 includes the SUCI of the UE 104, the CAGID of the requested CAG cell, and the other parameters in the Ncag_XXXRequest message and sends the Ncag_XXX Request message to the CAG server110.

On receiving the Ncag_XXX Request message, the CAG server 110 revealsthe SUCI to the SUPI and retrieves the allowed list of CAG cells/NPN 102b based on the revealed SUPI. Based on the retrieved allowed list of CAGcells and the CAG ID of the requested CAG cell, the CAG server 110verifies if the UE 104 has the permissions to access the requested CAGcell. If the UE 104 has the permissions to access the requested CAGcell, the CAG server 110 includes the accept message and the allowedlist of CAG cells to the AUSF 204 in the Ncag_XXX Response message. Onreceiving the accept message from the CAG server 110, the AUSF 204 mayfurther proceed with the registration request of the UE 104. If the UE104 does not have the permissions to access the requested CAG cell, theCAG server 110 includes the reject message and the allowed list of CAGcells to the AUSF 204 in the Ncag_XXX Response message. On receiving thereject message from the CAG server 110, the AUSF 204 includes the CAGcell reject message in the Nausf_XXX Response message and sends theNausf_XXX Response message to the AMF/SEAF 202. The AMF/SEAF 202 mayfurther reject the registration request of the UE 104.

Embodiments herein enable the CAG server 110 to verify the permissionsof the UE 104 to access the CAG cells/NPN 102 b on receiving the SUPIfrom the AMF/SEAF 202. The UE 104 initiates the request procedure foraccessing the CAG cells/NPN 102 b by sending the service request messageto the AMF/SEAF 202 through the NG-RAN 106 a. The AMF/SEAF 202 mayreceive the CAG ID of the requested CAG cell/NPN 102 b either from theNG-RAN 106 a or from the UE 104 in the registration request message. Onreceiving the request of the UE 104, the AMF/SEAF 202 may reveal theSUPI of the UE 104 (for example: from UE's 5G-GUTI or the like so). Ifthe AMF/SEAF 202 does not have information to verify the permissions ofthe UE 104 to access the CAG cell/NPN 102 b, the AMF/SEAF 202 providesthe SUPI of the UE 104 and the CAG ID of the requested CAG cell to theCAG server 110 in the Ncag_XXX Request message. On receiving the SUPIfrom the AMF/SEAF 202, the CAG server 110 retrieves the allowed list ofCAG cells for the UE 104. Based on the retrieved allowed list of CAGcells and the CAG ID of the requested CAG cell, the CAG server 110verifies if the UE 104 has the permissions to access the requested CAGcell. The CAG server 110 sends the result (accept/reject) of theverification to the AMF/SEAF 202 in the Ncag_XXX Response message. Basedon the response from the CAG server 110, the AMF/SEAF 202 may proceedfurther with the registration request of the UE 104 or reject theregistration request of the UE 104.

FIGS. 1A, B, 1C and 2 show various elements/nodes/components of thewireless network 100, but it is to be understood that other embodimentsare not limited thereon. In other embodiments, the wirelesscommunication system 100 may include less or a greater number of units.Further, the labels or names of the units are used only for illustrativepurpose and does not limit the scope of the embodiments herein. One ormore units can be combined together to perform same or substantiallysimilar function in the wireless network 100.

3GPP TS 23.501 specifies Public Network Integrated (Non-standalone)Non-Public Networks as Non-Public Networks (NPNs) which are deployedwith the support of public PLMNs using Closed Access Group (CAG) and/ornetwork slicing. When large number of UEs (especially inIndustrial/Cellular/Massive IoT), which are rogue or malfunctioning ormalicious (compromised or introduced by the attacker) with or withoutvalid subscription, not authorized to access the CAG cell, performsRegistration procedures to access the network via CAG cells, then thereis an overhead (signalling and also computational) on the network andespecially in the UDM, AMF and gNB, as the network needs to de-concealthe SUCI and perform authentication procedure and then check whether theUEs authorization for the CAG cell access. Such attempts in a particularCAG cell or distributed at different CAG cells to access the NPN via theCAG cell, will lead to (Distributed) Denial of Service ((D)DoS) attackon the 5G system. The present disclosure provides novel mechanism forthe network to verify an UE's Registration request via CAG cell withoutperforming primary authentication. This method enables the network(UDM/AUSF) to verify an UE's subscription to access a CAG cell (wherethe UE is requesting the access) based on UE's Subscription concealedidentifier (SUCI), before performing the primary authentication. The UDMreceives the CAG Identifier and the UE's Subscription identity, from theserving network AMF (via AUSF), and the UDM performs the CAG accesscheck before proceeding further with the authentication procedure. Byperforming the check at the UDM (instead of doing it at the servingnetwork (AMF)), minimizes the overhead on the network and (D)DoS attackon the network is mitigated without reducing the level of the 5GSsecurity. According to various embodiments, UDM performs the check onUE's access CAG cell and proceeds further with primary authenticationprocedure based on the result of CAG cell access check. Serving network(AMF) sends the CAG ID (Identifier of the CAG cell where the UE isrequesting access) to the UDM via AUSF.

FIG. 3 is a sequence diagram depicting verification of the permissionsof the UE 104 to access the CAG cell at the UDM of the 5GC 108 a,according to embodiments as disclosed herein. At step 301, the UE 104sends the registration request to the AMF/SEAF 202 through the NG-RAN106 a to access the CAG cell/NPN 102 b. The registration requestincludes the SUCI of the UE 104. In an embodiment, the UE 104 may alsosend the CAG ID of the requested CAG cell/NPN 102 b in the registrationrequest. In an embodiment, the NG-RAN 106 a may send all the CAG ID(s)of the serving CAG ID(s) along with the registration request to theAMF/SEAF 202.

At step 302, the AMF/SEAF 202 sends the authentication request(Nausf_UEAuthentication_Authenticate Request) message to the AUSF 204 byincluding the SUCI of the UE 104, the CAG ID of the requested CAG cell,and the other parameters (for example: SN-name or the like) in theauthentication request message.

At step 303, the AUSF 204 includes the received SUCI of the UE 104, theCAG ID of the requested CAG cell, and other parameters in theauthentication get request (Nudm_UEAuthentication_GetRequest) messageand sends the authentication get request message to the UDM/ARPF/SIDF206.

At step 304, the UDM/ARPF/SIDF 206 verifies the permissions orauthorization of the UE 104 to access the requested CAG cell/NPN 102 bon receiving the authentication get request message from the AUSF 204.In an embodiment, the UDM/ARPF/SIDF 206 verifies the permissions orauthorization of the UE 104 to access the requested CAG cell/NPN 102 bbefore performing the primary authentication procedure. TheUDM/ARPF/SIDF 206 reveals the received SUCI to the SUPI and retrievesthe allowed list of CAG cells based on the SUPI. The UDM/ARPF/SIDF 206verifies if the received CAG ID(s) of the requested CAG cell is presentin the allowed list of CAG cells based on the SUPI. On verifying thatthe received CAG ID(s) of the requested CAG cell is present in theallowed list of CAG cells based on the SUPI, the UDM/ARPF/SIDF 206determines that the UE has the permissions or subscription or the UE isthe authorized UE to access the CAG cell/NPN 102 b. Thereafter, theUDM/ARPF/SIDF 206 generates the authentication vector based on the SUPIof the UE 104 and performs the primary authentication procedure (asspecified in 3GPP TS 33.501) for authenticating the UE 104 in order toallow the UE 104 to access the NPN 102 b/services provided by the NPN102 b. On verifying that the received CAG ID of the requested CAG cellis not present in the allowed list of CAG cells based on the SUPI, theUDM/ARPF/SIDF 206 determines that the UE does not have the permissionsor subscription or the UE is not authorized to access the CAG cell/NPN102 b. Then, the UDM/ARPF/SIDF 206 includes the error information in theauthentication get response message (Nudm_UEAuthentication_GetResponse).

At step 305, the UDM/ARPF/SIDF 206 sends the authentication get responsemessage (for example: 403 Forbidden or the like) to the AUSF. At step306, the AUSF 204 inserts the reject message of the receivedauthentication get response message in the authentication response(Nausf_UEAUthentication_Authenticate Response). The AUSF 204 sends theauthentication response (for example: 403 Forbidden or the like) to theAMF/SEAF 202. At step 307, the AMF/SEAF 202 rejects the registrationrequest of the UE 104 on receiving the reject message from the AUSF 204.The AMF/SEAF 202 sends the reject message with the appropriate causevalue (for example: #12, #13 , #15 , #76 or the like) to the UE 104,wherein the appropriate cause value indicating that the CAG cell accessis not allowed. Thus, verifying the permissions/authorization of the UE104 to access the CAG cell at the UDM before performing the primaryauthentication minimizes the signaling overhead on the 5GC 108 a andmitigates the DoS attack.

According to various embodiments, a method for controlling permissionsof at least one User Equipment (UE) to access at least one Non-PublicNetwork (NPN) in a network, the method comprises: requesting, by the atleast one UE, a Public Land Mobile Network (PLMN) for accessing the atleast one NPN through at least one Closed Access Group (CAG) cell;verifying, by a Core Network (CN) of the PLMN, the permissions of the atleast one UE for accessing the requested at least one NPN through the atleast one CAG cell; and performing, by the CN, a primary authenticationprocedure to allow the at least one UE to access the at least one NPNthrough the at least one CAG cell based on the permissions of the atleast one UE for accessing the requested at least one NPN through the atleast one CAG cell being verified.

In some embodiments, the at least one NPN is deployed in conjunctionwith the PLMN using the at least one CAG cell.

In some embodiments, the at least one NPN includes at least one of anon-standalone NPN or a stand-alone NPN.

In some embodiments, at least one of a unified data management (UDM), anaccess and mobility management function (AMF), or an authenticationserver function (AUSF) of the CN verifies the permissions of the atleast one UE to access the requested at least one NPN through the atleast one CAG cell.

In some embodiments, a CAG server coupled to the CN verifies thepermissions of the at least one UE to access the requested at least oneNPN.

In some embodiments, requesting, by the at least one UE, the access tothe at least one NPN includes sending a request including a subscriptionconcealed identifier (SUCI) of the at least one UE to a Radio AccessNetwork (RAN) of the PLMN.

In some embodiments, the method further comprises: adding, by a RadioAccess Network (RAN), at least one CAG Identifier (CAG ID) of the atleast one NPN that is requested by the at least one UE; and sending, bythe RAN, a received subscription concealed identifier (SUCI) of the UEand the at least one CAG ID of the requested at least one NPN to the CN.

In some embodiments, requesting, by the at least one UE, the access tothe at least one NPN includes sending the request including asubscription concealed identifier (SUCI) of the at least one UE and atleast one CAG Identifier (CAG ID) of the requested at least one NPN to aRadio Access Network (RAN) of the PLMN.

In some embodiments, the CN verifies the permissions of the at least oneUE for accessing the at least one NPN based on the received requestmessage including the at least one CAG ID.

In some embodiments, verifying, by the CN, the permissions of the atleast one UE includes: receiving a subscription concealed identifier(SUCI) of the at least one UE and at least one CAG Identifier (CAG ID)of the requested at least one NPN from a Radio Access Network (RAN),deriving an allowed list of CAG cells for the at least one UE based onthe received SUCI of the at least one UE; and verifying the permissionsof the at least one UE to access the requested at least one NPN usingthe derived allowed list of CAG cells and the received at least one CAGID of the requested at least one NPN.

In some embodiments, deriving the allowed list of CAG cells for the atleast one UE includes: revealing the received SUCI of the at least oneUE to a subscription permanent identifier (SUPI); mapping the revealedSUPI of the at least one UE with a map of the allowed list of CAG cellsand the SUPIs of a plurality of UEs; and deriving the allowed list ofCAG cells for the at least one UE based on the associated SUPI mappingwith the revealed SUPI of the at least one UE.

In some embodiments, verifying the permissions of the at least one UEusing the derived allowed list of CAG cells and the received CAG ID ofthe requested at least one NPN includes: determining the received atleast one CAG ID of the requested at least one NPN is present in thederived allowed list of CAG cells; verifying that the at least one UEhas the permissions for accessing the requested at least one NPN basedon the at least one received CAG ID of the requested at least one NPNbeing present in the derived allowed list of CAG cells; and verifyingthat the at least one UE does not have the permissions for accessing therequested at least one NPN based on the received at least one CAG ID ofthe requested at least one NPN not being present in the derived allowedlist of CAG cells.

In some embodiments, the method further comprises rejecting the requestof the at least one UE on verifying that the at least one UE does nothave the permissions for accessing the requested at least one NPN; andsending a reject message to the at least one UE with a cause value,wherein the cause value indicates at least one cause of an error forrejecting the request of the at least one UE.

In some embodiments, performing the primary authentication procedureincludes: generating an authentication vector based on a revealedsubscription permanent identifier (SUPI) of the at least one UE based onverifying that the at least one UE has the permissions for accessing therequested at least one NPN; authenticating the at least one UE based onthe generated authentication vector based on determining that the atleast one UE has NPN permissions to access the requested at least oneNPN through the PLMN; and enabling the at least one UE to access therequested at least one NPN based on the at least one UE having the NPNpermissions to access the requested at least one NPN through the PLMN.

According to various embodiments, a network comprises at least one UserEquipment (UE); at least one Non-Public network (NPN); and a Public LandMobile Network (PLMN). The at least one NPN is deployed in conjunctionwith the PLMN, the PLMN includes at least one cellular networkcomprising of a Radio Access Network (RAN) and a Core Network (CN), theat least one UE is configured to request the PLMN for accessing the atleast one NPN through at least one Closed Access Group (CAG) cell, andthe CN is configured to: verify permissions of the at least one UE foraccessing the requested at least one NPN via the at least one CAG cell,and perform a primary authentication procedure to allow the at least oneUE to access the at least one NPN through the at least one CAG cell,based on the permissions of the at least one UE for accessing therequested at least one NPN through the at least one CAG cell beingverified.

In some embodiments, the at least one NPN is deployed in conjunctionwith the PLMN using the at least one CAG cell.

In some embodiments, the at least one NPN includes at least one of anon-standalone NPN or a stand-alone NPN.

In some embodiments, at least one of a unified data management (UDM), anaccess and mobility management function (AMF), or an authenticationserver function (AUSF) of the CN is further configured to verify thepermissions of the at least one UE to access the requested at least oneNPN through the at least one CAG cell.

In some embodiments, the PLMN further comprises a CAG server coupledwith the CN configured to verify the permissions of the at least one UEto access the requested at least one NPN.

In some embodiments, the at least one UE is further configured to send arequest including a subscription concealed identifier (SUCI) of the atleast one UE to the RAN of the PLMN requesting access to the at leastone NPN.

In some embodiments, the at least one RAN is further configured to: addat least one CAG identifier (CAG ID) of the at least one NPN that isrequested by the at least one UE; and send a received subscriptionconcealed identifier (SUCI) of the UE and the CAG ID of the requested atleast one NPN to the CN.

In some embodiments, the at least one UE is further configured to sendthe request including a subscription concealed identifier (SUCI) of theat least one UE and a CAG Identifier (CAG ID) of the requested at leastone NPN to the RAN of the PLMN.

In some embodiments, the CN is further configured to verify thepermissions of the at least one UE for accessing the at least one NPNbased on the received request messages including the at least one CAGID.

In some embodiments, the CN is further configured to: receive asubscription concealed identifier (SUCI) of the at least one UE and atleast one CAG Identifier (CAG ID) of the requested at least one NPN fromthe RAN; derive an allowed list of CAG cells for the at least one UEbased on the received SUCI of the at least one UE; and verify thepermissions of the at least one UE to access the requested at least oneNPN using the derived allowed list of CAG cells and the received atleast one CAG ID of the requested at least one NPN.

In some embodiments, the CN is further configured to: reveal thereceived SUCI of the at least one UE to a subscription permanentidentifier (SUPI); map the revealed SUPI of the at least one UE with amap of the allowed list of CAG cells and the SUPIs of a plurality ofUEs; and derive the allowed list of CAG cells for the at least one UEbased on the associated SUPI mapping with the revealed SUPI of the atleast one UE.

In some embodiments, the CN is further configured to: determine thereceived at least one CAG ID of the requested at least one NPN ispresent in the derived allowed list of CAG cells; verify that the atleast one UE has the permissions for accessing the requested at leastone NPN based on the received at least one CAG ID of the requested atleast one NPN being present in the derived allowed list of CAG cells;and verify that the at least one UE does not have the permissions foraccessing the requested at least one CAG cell of the at least one NPNbased on the received CAG ID of the requested at least one NPN not beingpresent in the derived allowed list of CAG cells.

In some embodiments, the CN is further configured to: reject the requestof the at least one UE on verifying that the at least one UE does nothave the permissions for accessing the requested at least one CAG ID ofthe at least one NPN; and send a reject message to the at least one UEwith a cause value, wherein the cause value indicates at least one causeof an error for rejecting the request of the at least one UE.

In some embodiments, the CN is further configured to: generate anauthentication vector based on a received subscription permanentidentifier (SUPI) of the at least one UE based on verifying that the atleast one UE has the permissions for accessing the requested at leastone NPN; authenticate the at least one UE based on the generatedauthentication vector based on determining that the at least one UE hasNPN permissions to access the requested at least one NPN through thePLMN; and enable the at least one UE to access the requested at leastone NPN based on the at least one UE having the NPN permissions toaccess the requested at least one NPN through the PLMN.

According to various embodiments, a network comprises at least one UserEquipment (UE); at least one Non-Public Network (NPN); and a Public LandMobile Network (PLMN). The at least one NPN is deployed in conjunctionwith the PLMN through at least one Closed Access Group (CAG) cell, thePLMN includes at least one cellular network comprising of a Radio AccessNetwork (RAN) and a Core Network (CN), the at least one UE is configuredto request the PLMN for an access to the at least one NPN, and the CNcomprises a unified data management (UDM) configured to: verifypermissions of the at least one UE to access the requested at least oneNPN, and initiate a primary authentication procedure based on thepermissions of the at least one UE to access the requested at least oneNPN being verified.

In some embodiments, the at least one UE is further configured to send arequest including a subscription concealed identifier (SUCI) of the atleast one UE to the RAN of the PLMN requesting access to the at leastone NPN, and the RAN is configured to: add a CAG Identifier (CAG ID) ofthe at least one NPN that is requested by the at least one UE, and senda received subscription concealed identifier (SUCI) of the UE and theCAG ID of the requested at least one NPN to the CN.

In some embodiments, the at least one UE is further configured to sendthe request including a subscription concealed identifier (SUCI) of theat least one UE and a CAG Identifier (CAG ID) of the requested at leastone NPN to the RAN of the PLMN.

In some embodiments, the CN further comprises an access and mobilitymanagement function (AMF) and an authentication server function (AUSF),the AMF is configured to: receive the SUCI of the at least one UE andthe CAG ID of the requested at least one NPN from the RAN, insert thereceived SUCI of the at least one UE and the CAG ID of the requested atleast one NPN in a first authentication request message, and send thefirst authentication request message to the AUSF, and the AUSF isfurther configured to: derive the SUCI of the at least one UE and theCAG ID of the requested at least one NPN from the received firstauthentication request message, insert the derived SUCI of the at leastone UE and the CAG ID of the requested at least one NPN in a firstauthentication get request message, and send the authentication getrequest message to the UDM.

In some embodiments, the UDM is further configured to: receive the SUCIof the at least one UE and the CAG ID of the requested at least one NPNfrom the AUSF, reveal the received SUCI of the at least one UE to asubscription permanent identifier (SUPI), map the revealed SUP of the atleast one UE with a map of an allowed list of CAG cells and the SUPIs ofa plurality of UEs, retrieve the allowed list of CAG cells for the atleast one UE based on the associated SUPI mapping with the revealed SUPIof the at least one UE, verify that the at least one UE has thepermissions to access the requested at least one NPN based on thereceived CAG ID of the requested at least one NPN being present in theretrieved allowed list of CAG cells, and verify that the at least one UEdoes not have the permissions to access the requested at least one NPNbased on the received CAG ID of the requested at least one NPN not beingpresent in the retrieved allowed list of CAG cells.

In some embodiments, the UDM is further configured to: insert a rejectmessage and the SUPI of the at least one UE in a second authenticationget request message based on verifying that the at least one UE does nothave the access to the requested at least one NPN, and send theauthentication get response message to the AUSF, the AUSF is furtherconfigured to: derive the reject message from the received secondauthentication get response message and insert the derived rejectmessage in a second authentication response message, and send the secondauthentication response message to the AMF, and the AMF is furtherconfigured to: reject the request of the at least one UE based onreceiving the reject message from the AUSF; and send a reject message tothe at least one UE through the RAN with a cause value, wherein thecause value indicates at least one cause of an error for rejecting therequest of the at least one UE.

In some embodiments, the UDM is further configured to: generate anauthentication vector based on the received SUCI of the at least one UEbased on verifying the at least one UE has the permissions to access therequested at least one NPN, and send the authentication vector to theAMF through the AUSF, and the AMF is further configured to: authenticatethe at least one UE based on the received authentication vector todetermine based on the at least one UE having NPN permissions to accessthe requested at least one NPN through the PLMN; and enable the at leastone UE to access the at least one requested NPN based on the at leastone UE having the NPN permissions to access the requested at least oneNPN through the PLMN.

According to various embodiments, a core network (CN) of a Public LandMobile Network (PLMN), wherein the PLMN is in conjunction with at leastone non-public network (NPN) and connected to at least one UserEquipment (UE), wherein the CN is configured to: receive a request fromthe at least one UE through a Radio Access Network (RAN) for access tothe at least one NPN; verify permissions of the at least one UE toaccess the requested at least one NPN; and perform a primaryauthentication procedure based on the permissions of the at least one UEto access the requested at least one NPN being verified.

In some embodiments, the request of the at least one UE includes asubscription concealed identifier (SUCI) of the at least one UE and aClosed Access Group (CAG ID) of the at least one NPN that is requestedby the at least one UE.

In some embodiments, the CN is further configured to: reveal a receivedsubscription concealed identifier (SUCI) of the at least one UE to asubscription permanent identifier (SUPI), map the revealed SUPI of theat least one UE with a map of an allowed list of CAG cells and the SUPIsof a plurality of UEs, retrieve the allowed list of CAG cells for the atleast one UE based on the associated SUPI mapping with the revealed SUPIof the at least one UE, verify that the at least one UE has thepermissions to access the requested at least one NPN based on receivinga Closed Access Group Identifier (CAG ID) of the requested at least oneNPN being present in the retrieved allowed list of CAG cells, and verifythat the at least one UE does not have the permissions to access therequested at least one NPN based on the received CAG ID of the requestedat least one NPN not being present in the retrieved allowed list of CAGcells.

In some embodiments, the CN is further configured to: reject the requestof the at least one UE based on verifying that the at least one UE doesnot have the permissions to access the requested at least one NPN, andsend a reject message to the at least one UE through the RAN with acause value, wherein the cause value indicating at least one cause of anerror for rejecting the request of the at least one UE.

FIG. 4 is a sequence diagram depicting the verification of thepermissions of the UE 104 to access the CAG cell at the UDM 206 of the5GC 108 a by directly communicating with the AMF/SEAF 202, according toembodiments as disclosed herein. At step 401, the UE 104 sends theregistration request including the SUCI to the AMF/SEAF 202 through theNG-RAN 106 a for accessing the CAG cell/NPN 102 b. The NG-RAN 106 a mayalso send the CAG ID of the requested CAG cell/NPN 102 b to the AMF/SEAF202 or the UE 104 may send the CAG ID of the requested CAG cell/NPN 102b to the AMF/SEAF 202 through the NG-RAN 106 a.

At step 402, the AMF/SEAF 202 inserts the received SUCI of the UE 104,the CAG ID, and the other parameters (like SN name) in the Nudm_XXXrequest message and sends the Nudm_XXX request message to the UDM 206.

At step 403, the UDM 206 verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b on receiving the authenticationget request message from the AMF/SEAF 202. In an embodiment, the UDM 206verifies the permissions of the UE 104 to access the requested CAGcell/NPN 102 b before performing the primary authentication procedure.The UDM 206 reveals the received SUCI to the SUPI and retrieves theallowed list of CAG cells based on the SUPI. The UDM 206 verifies if theUE 104 has the permissions to access the requested CAG cell/NPN 102 bbased on the allowed list of CAG cells retrieved based on the SUPI ofthe UE 104, and the CAG ID of the requested CAG cell. On verifying thatthe UE 104 has permissions to the requested CAG cell, the UDM 206inserts the accept message, the allowed list of CAG cells for the UE104, or the like in the Nudm_XXX response message. At step 404 a, theUDM 206 sends the Nudm_XXX response message to the AMF/SEAF 202indicating the successful verification. At step 405 a, on receiving theNudm_XXX response message, the AMF/SEAF 202 proceeds further with theregistration request of the UE 104. At step 406 a, the AMF/SEAF 202performs the primary authentication procedure (as specified in 3GPP TS33.501) for authenticating the UE 104 in order to allow the UE 104 toaccess the NPN 102 b/services provided by the NPN 102 b.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the UDM 206 includes the reject message indicatingthat the UE 104 is not permitted to use the CAG cell and the cause valuein the Nudm_XXX response message. At step 404 b, the UDM 206 sends theNudm_XXX response message to the AMF/SEAF 202 indicating theunsuccessful verification. At step 405 b, the AMF/SEAF 202 rejects theregistration request of the UE 104. At step 406 b, the AMF/SEAF 202sends the response with the reject message and the appropriate causevalue to the UE 104.

FIG. 5 is a sequence diagram depicting the verification of thepermissions of the UE 104 to access the CAG cell at the UDM 206 bycommunicating with the AMF/SEAF 202 over get request message and getresponse messages, according to embodiments as disclosed herein. At step501, the UE 104 sends the registration request including the SUCI to theAMF/SEAF 202 through the NG-RAN 106 a for accessing the CAG cell/NPN 102b. The NG-RAN 106 a may also send the CAG ID of the requested CAGcell/NPN 102 b to the AMF/SEAF 202 or the UE 104 may send the CAG ID ofthe requested CAG cell/NPN 102 b to the AMF/SEAF 202 through the NG-RAN106 a.

At step 502, the AMF/SEAF 202 inserts the received SUCI of the UE 104,the CAG ID, and the other parameters (like SN name) in theNudm_UEVerifyCAGAccess_Get request message and sends theNudm_UEVerifyCAGAccess_Get request message to the UDM 206.

At step 503, the UDM 206 verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b on receiving the authenticationget request message from the AMF/SEAF 202. In an embodiment, the UDM 206verifies the permissions of the UE 104 to access the requested CAGcell/NPN 102 b before performing the primary authentication procedure.The UDM 206 reveals the received SUCI to the SUPI and retrieves theallowed list of CAG cells based on the SUPI. The UDM 206 verifies if theUE 104 has the permissions to access the requested CAG cell/NPN 102 bbased on the allowed list of CAG cells retrieved based on the SUPI ofthe UE 104, and the CAG ID of the requested CAG cell. On verifying thatthe UE 104 has permissions to the requested CAG cell, the UDM 206inserts the accept message, the allowed list of CAG cells for the UE104, or the like in the Nudm_UEVerifyCAGAccess_Get Response message. Atstep 504 a, the UDM 206 sends the Nudm_UEVerifyCAGAccess_Get Responsemessage to the AMF/SEAF 202 indicating the successful verification. Atstep 505 a, on receiving the Nudm_XXX response message, the AMF/SEAF 202proceeds further with the registration request of the UE 104.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the UDM 206 includes the reject message indicatingthat the CAG cell is not allowed for the UE 104 and the cause value inthe Nudm_XXX response message. At step 504 b, the UDM 206 sends theNudm_XXX response message to the AMF/SEAF 202 indicating theunsuccessful verification. At step 505 b, the AMF/SEAF 202 rejects theregistration request of the UE 104. At step 506, the AMF/SEAF 202 sendsthe response with the reject message and the appropriate cause value tothe UE 104.

FIG. 6 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the UDM 206 and/or the AUSF 204 ofthe 5GC 108 a, according to embodiments as disclosed herein. At step601, the UE 104 sends the registration request to the AMF/SEAF 202through the NG-RAN 106 a to access the CAG cell/NPN 102 b. Theregistration request includes the SUCI of the UE 104. In an embodiment,the UE 104 may also send the CAG ID of the requested CAG cell/NPN 102 bin the registration request to the AMF/SEAF 202 through the NG-RAN 106a. In an embodiment, the NG-RAN 106 a may send the CAG ID of therequested CAG cell/NPN 102 b along with the registration request to theAMF/SEAF 202.

At step 602, the AMF/SEAF 202 inserts the received SUCI of the UE 104,the CAG ID, and the other parameters in the Nausf_XXX request messageand sends the Nausf_XXX request message to the AUSF 204. At step 603,the AUSF 204 inserts the SUCI, the CAG ID, and the other parameters ofthe received Nausf_XXX message in the Nudm_XXX request message. The AUSF204 sends the Nudm_XXX request message to the UDM 206.

At step 604, the UDM 206 reveals the received SUCI to the SUPI andretrieves the allowed list of CAG cells for the UE 104 based on theSUPI. In an embodiment, the UDM 206 verifies the permissions of the UE104 to access the requested CAG cell/NPN 102 b using the allowed list ofCAG cells for the UE 104 retrieved based on the SUPI and the receivedCAG ID of the requested CAG cell/NPN 102 b. On verifying that that theUE has the permissions to access the CAG cell/NPN 102 b, the UDM 206initiates the primary authentication procedure (as specified in 3GPP TS33.501) for authenticating the UE 104 in order to allow the UE 104 toaccess the NPN 102 b/services provided by the NPN 102 b. On verifyingthat the UE 104 does not have the permissions to access the CAG cell/NPN102 b, the UDM 206 includes the CAG cell reject message indicating thatthe CAG cell is not allowed for the UE 104 and the SUPI of the UE in theNudm_XXX response message. At step 605, the UDM 206 sends the Nudm_XXXresponse message indicating that the CAG cell is not allowed to the AUSF204.

In an embodiment, the UDM 206 may send the retrieved allowed list of CAGcells to the AUSF 204 for performing the verification of the permissionsof the UE 104. In such a case, at step 605, the UDM 206 sends theNudm_XXX response message including the allowed list of CAG cells to theAUSF 204.

At step 606, the AUSF 204 verifies the permissions of the UE 104 toaccess the CAG cells/NPN 102 b using the received allowed list of CAGcells and the CAG ID of the requested CAG cell/NPN 102 b.

At step 607, the AUSF 204 sends the CAG cell reject in the Nausf_XXXresponse message to the AMF/SEAF 202 on verifying that the UE 104 doesnot have the permissions to access the CAG cell or receiving theNudm_XXX response indicating that the CAG cell access is not allowedfrom the UDM 206. At step 608, the AMF/SEAF 202 rejects the registrationrequest of the UE 104 by sending the reject message and the appropriatecause value to the UE 104.

FIG. 7 is a sequence diagram depicting verification of the permissionsof the UE 104 to access the CAG cell at the AUSF 204 of the 5GC 108 a,according to embodiments as disclosed herein. At step 701, the UE 104sends the registration request to the AMF/SEAF 202 through the NG-RAN106 a to access the CAG cell/NPN 102 b. The registration requestincludes the SUCI of the UE 104. In an embodiment, the UE 104 may alsosend the CAG ID of the requested CAG cell/NPN 102 b in the registrationrequest to the AMF/SEAF through the NG-RAN 106 a. In an embodiment, theNG-RAN may send the CAG ID of the requested CAG cell/NPN 102 b alongwith the registration request to the AMF/SEAF 202.

At step 702, the AMF/SEAF 202 inserts the received SUCI of the UE 104,the CAG ID, and the other parameters in theNausf_UEAuthentication_Authenticate Request message and sends theNausf_UEAuthentication_Authenticate Request message to the AUSF 204. Atstep 703, the AUSF 204 inserts the SUCI, the CAG ID, and the otherparameters of the received Nausf_UEAuthentication_Authenticate Requestin the Nudm_UEAuthentication_Get Request message. The AUSF 204 sends theNudm_UEAuthentication_Get Request message to the UDM 206.

At step 704, the UDM 206 reveals the received SUCI to the SUPI andretrieves the allowed list of CAG cells for the UE 104 based on theSUPI. At step 705, the UDM 206 inserts the SUPI of the UE 104 and theallowed list of CAG cells in the Nudm_UE authentication_Get Response andsends the Nudm_UE authentication_Get Response to the AUSF 204.

At step 706, the AUSF 204 verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b using the received allowed listof CAG cells for the UE 104 and the received CAG ID of the requested CAGcell/NPN 102 b. On verifying that the UE 104 has the permissions toaccess the CAG cell/NPN 102 b, the AUSF 204 initiates the primaryauthentication procedure (as specified in 3GPP TS 33.501) forauthenticating the UE 104 in order to allow the UE 104 to access the NPN102 b/services provided by the NPN 102 b. On verifying that the UE 104does not have the permissions to access the CAG cell/NPN 102 b, the AUSF204 includes the CAG cell reject message indicating that the CAG cell isnot allowed for the UE 104 in the Nausf_UEAuthentication_AuthenticateResponse message. At step 707, the AUSF 204 sends theNausf_UEAuthentication_Authenticate Response message to the AMF/SEAF 202indicating that the CAG cell is not allowed.

At step 708, the AMF/SEAF 202 rejects the registration request of the UE104 by sending the reject message and the appropriate cause value to theUE 104.

FIG. 8 is a sequence diagram depicting verification of the permissionsof the UE 104 to access the CAG cell at the CAG server 110 on receivingthe request from the UDM 206, according to embodiments as disclosedherein. At step 801, the UDM 206 receives the registration request ofthe UE 104 requesting the access to the CAG cell/NPN 102 b, wherein theregistration request includes the SUCI of the UE 104 and the CAG ID ofthe requested CAG cell/NPN 102 b. The UDM 206 derives the SUPI of the UE104 from the received SUCI. At step 802, the UDM 206 inserts the SUPI ofthe UE 104 and the CAG ID of the requested CAG cell/NPN 102 b in theNcag_XXX Request message. At step 803, the UDM 206 sends the Ncag_XXXRequest message to the CAG server 110.

At step 804, the CAG server 110 obtains the allowed list of CAG cellsfor the UE 104 based on the received SUPI of the UE 104 from the UDM206. The CAG server 110 verifies the permissions of the UE 104 to accessthe CAG cell/NPN 102 b based on the allowed list of CAG cells and theCAG ID of the requested CAG cell. On verifying that the UE 104 has thepermissions to verify the requested CAG cell/NPN 102 b, the CAG server110 inserts the accept message in the Ncag_XXX Response message. At step805, the CAG server 110 sends the Ncag_XXX Response message includingthe accept message to the UDM 206. At step 806, the UDM 206 may proceedfurther with the request procedure.

On verifying that the UE 104 does not have the permissions to verify therequested CAG cell/NPN 102 b, the CAG server inserts the reject messagein the Ncag_XXX Response message. At step 805, the CAG server 110 sendsthe Ncag_XXX Response message including the reject message to the UDM206 indicating that the CAG cell access is not allowed. At step 806, theUDM 206 may reject the registration request of the UE 104 with theappropriate cause value.

FIG. 9 is a sequence diagram depicting verification of the permissionsof the UE 104 to access the CAG cell at the CAG server 110 on receivingthe SUCI of the UE 104 from the AMF/SEAF 202, according to embodimentsas disclosed herein. At step 901, the UE 104 sends the registrationrequest to the AMF/SEAF 202 through the NG-RAN 106 a to access the CAGcell/NPN 102 b. The registration request includes the SUCI of the UE104. In an embodiment, the UE 104 may also send the CAG ID of therequested CAG cell/NPN 102 b in the registration request to the AMF/SEAF202 through the NG-RAN 106 a. In an embodiment, the NG-RAN 106 a maysend the CAG ID of the requested CAG cell/NPN 102 b along with theregistration request to the AMF/SEAF 202. The AMF/SEAF 202 sends thereceived SUCI of the UE 104 and the CAG ID of the requested CAG cell/NPN102 b to the CAG server 110.

At step 902, the CAG server 110 inserts the received SUCI in theNudm_XXX request message and sends the Nudm_XXX request message to theUDM 206. At step 903, the UDM 206 reveals the SUCI to the SUPI. At step904, the UDM 206 sends the revealed SUPI to the CAG server 110 over theNudm_XXX response message.

At step 905, the CAG server 110 obtains the allowed list of CAG cellsfor the UE 104 based on the received SUPI of the UE 104 from the UDM206. The CAG server 110 verifies the permissions of the UE 104 to accessthe CAG cell/NPN 102 b based on the allowed list of CAG cells and theCAG ID of the requested CAG cell. At step 906, the CAG server 110 sendsthe results (accept and/or reject) of the verification to the AMF/SEAF202. The AMF/SEAF 202 proceeds further with the registration request ofthe UE 104 if the result of the verification is accepted or the AMF/SEAF202 rejects the registration request of the UE 104 if the result of theverification is rejected.

FIG. 10 is a sequence diagram depicting verification of the permissionsof the UE 104 to access the CAG cell at the CAG server 110 on receivingthe SUCI of the UE 104 from the AUSF 204, according to embodiments asdisclosed herein. At step 1001, the UE 104 sends the service request tothe AMF/SEAF 202 through the NG-RAN 106 a requesting the access for theCAG cell/NPN 102 b. In an embodiment, the UE 104 may also send the CAGID of the requested CAG cell/NPN 102 b in the registration request tothe AMF/SEAF 202 through the NG-RAN 106 a. In an embodiment, the NG-RAN106 a may send the CAG ID of the requested CAG cell/NPN 102 b along withthe registration request to the AMF/SEAF 202.

At step 1002, the AMF/SEAF 202 inserts the SUPI of the UE 104, the CAGID of the requested CAG cell, and the other parameters (like SN name) inthe Nausf_XXX Request message and sends the Nausf_XXX Request message tothe AUSF 204.

At step 1003, the AUSF 204 derives the SUPI of the UE 104, the CAG ID ofthe requested CAG cell, and the other parameters (like SN name) from thereceived Nausf_XXX Request message. The AUSF 204 inserts the SUPI of theUE 104, the CAG ID of the requested CAG cell, and the other parameters(like SN name) in the NCag_XXX Request message and sends the NCag_XXXRequest message to the CAG server 110.

At step 1004, the CAG server 110 verifies the permissions of the UE 104to access the requested CAG cell/NPN 102 b on receiving the NCag_XXXRequest message from the AUSF 204. In an embodiment, the CAG server 110verifies the permissions of the UE 104 to access the requested CAGcell/NPN. The CAG server 110 retrieves the allowed list of CAG cellsbased on the received SUPI. The CAG server 110 verifies if the UE 104has the permissions to access the requested CAG cell/NPN 102 b based onthe allowed list of CAG cells retrieved based on the SUPI of the UE 104,and the CAG ID of the requested CAG cell. On verifying that the UE 104has permissions to the requested CAG cell, the CAG server 110 insertsthe accept message, the allowed list of CAG cells for the UE 104, or thelike in the NCag_XXX Response message. At step 1005, the CAG server 110sends the NCag_XXX Response message to the AUSF 204 indicating thesuccessful verification. At step 1006, the AUSF 204 may proceed furtherwith the registration request of the UE 104 on receiving the acceptmessage from the CAG server 110.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the CAG server 110 inserts the reject message in theNCag_XXX Response message. At step 1005, the CAG server 110 sends theNCag_XXX Response message including the reject message to the AUSF 204indicating that the CAG cell is not allowed for the UE 104.

At step 1006, the AUSF 204 rejects the service request of the UE 104 onreceiving the reject message from the CAG server 110. At step 1007, theAUSF 204 sends the Nausf_XXX Response message including the CAG cellreject to the AMF/SEAF 202 on receiving the reject message from the CAGserver 110.

At step 1008, the AMF/SEAF 202 rejects the registration request of theUE 104 by sending the reject message and the appropriate cause value tothe UE 104 on receiving the reject message from the AUSF 204.

FIG. 11 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the AMF/SEAF 202, according toembodiments as disclosed herein. At step 1101, the UE 104 sends theregistration request to the AMF/SEAF 202 through the NG-RAN 106 arequesting the access for the CAG cell/NPN 102 b. The registrationrequest includes the SUCI of the UE 104. In an embodiment, the UE 104may also send the CAG ID of the requested CAG cell/NPN 102 b in theregistration request to the AMF/SEAF 202 through the NG-RAN 106 a. In anembodiment, the NG-RAN 106 a may send the CAG ID of the requested CAGcell/NPN 102 b along with the registration request to the AMF/SEAF 202.

At step 1102, the AMF/SEAF 202 inserts the received SUCI of the UE 104in the Nudm_XXX Request message and sends the Nudm_XXX Request messageto the UDM 206.

At step 1103, the UDM 206 reveals the received SUCI of the UE 104 to theSUPI and retrieves the allowed list of CAG cells for the UE 104 based onthe SUPI. If the revealed SUPI is valid, the UDM 206 stores the SUCI tothe SUPI mapping, which may be used during the primary authenticationprocedure. At step 1104, the UDM 206 sends the SUPI and the allowed listof CAG cells for the UE 104 to the AMF/SEAF 202 over the Nudm_XXXResponse message.

At step 1105, the AMF/SEAF 202 verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b based on the received allowedlist of CAG cells and the CAG ID of the requested CAG cell/NPN 102 b.

At step 1106, the AMF/SEAF 202 proceeds further with the registrationrequest of the UE 104 on verifying that the UE has the permissions toaccess the CAG cells.

At step 1107, the AMF/SEAF 202 rejects the registration request of theUE 104 by sending the reject message with the appropriate cause value tothe UE 104 on verifying that the UE 104 does not have the permissions toaccess the CAG cells.

FIG. 12 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the AMF/SEAF 202 by communicatingwith the UDM 206 over the service interface provided by the UDM 206,according to embodiments as disclosed herein. At step 1201, the UE 104sends the registration request to the AMF/SEAF 202 through the NG-RAN106 a requesting the access for the CAG cell/NPN 102 b. The registrationrequest includes the SUCI of the UE 104. In an embodiment, the UE 104may also send the CAG ID of the requested CAG cell/NPN 102 b in theregistration request to the AMF/SEAF 202 through the NG-RAN 106 a. In anembodiment, the NG-RAN 106 a may send the CAG ID of the requested CAGcell/NPN 102 b along with the registration request to the AMF/SEAF 202.

At step 1202, the AMF/SEAF 202 inserts the received SUCI of the UE 104in the Nudm_SDM_Get Request message and sends the Nudm_SDM_Get Requestmessage to the UDM 206.

At step 1203, the UDM 206 reveals the received SUCI of the UE 104 to theSUPI and retrieves the allowed list of CAG cells for the UE 104 based onthe SUPI. If the revealed SUPI is valid, the UDM 206 stores the SUCI tothe SUPI mapping, which may be used during the primary authenticationprocedure. At step 1204, the UDM sends the SUPI and the allowed list ofCAG cells for the UE 104 to the AMF/SEAF 202 over the Nudm_SDM_GetResponse message.

At step 1205, the AMF/SEAF 202 verifies the permissions of the UE 104 toaccess the requested CAG cell/NPN 102 b based on the received allowedlist of CAG cells and the CAG ID of the requested CAG cell/NPN 102 b.

At step 1206, the AMF/SEAF 202 proceeds further with the registrationrequest of the UE 104 on verifying that the UE has the permissions toaccess the CAG cells.

At step 1207, the AMF/SEAF 202 rejects the registration request of theUE 104 by sending the reject message with the appropriate cause value tothe UE 104 on verifying that the UE 104 does not have the permission toaccess the CAG cells or if the AMF/SEAF 202 does not receive the SUPIfrom the UDM 206.

FIG. 13 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the CAG server by communicatingdirectly with the AMF/SEAF 202, according to embodiments as disclosedherein. At step 1301, the UE 104 sends the service request to theAMF/SEAF 202 through the NG-RAN 106 a requesting the access for the CAGcell/NPN 102 b. In an embodiment, the UE 104 may also send the CAG ID ofthe requested CAG cell/NPN 102 b in the request message to the AMF/SEAF202 through the NG-RAN 106 a. In an embodiment, the NG-RAN 106 a maysend the CAG ID of the requested CAG cell/NPN 102 b along with theregistration request to the AMF/SEAF 202.

At step 1302, the AMF/SEAF 202 reveals the SUPI of the UE 104. TheAMF/SEAF 202 inserts the revealed SUPI of the UE 104, the CAG ID of therequested CAG cell/NPN 102 b in the Nudm_XXX Request message and sendsthe Nudm_XXX Request message to the CAG server 110.

At step 1303, the CAG server 110 retrieves the allowed list of CAG cellsbased on the received SUPI. The CAG server 110 verifies if the UE 104has the permissions to access the requested CAG cell/NPN 102 b based onthe allowed list of CAG cells retrieved based on the SUPI of the UE 104,and the CAG ID of the requested CAG cell. On verifying that the UE 104has the permissions to the requested CAG cell, the CAG server 110inserts the accept message, and the allowed list of CAG cells for the UE104 in the NCag_XXX Response message. At step 1304, the CAG server 110sends the NCag_XXX Response message to the AMF/SEAF 202 indicating thesuccessful verification. At step 1305, the AMF/SEAF 202 may proceedfurther with the registration request of the UE 104 on receiving theaccept message from the CAG server.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the CAG server 110 inserts the reject message in theNCag_XXX Response message. At step 1304, the CAG server 110 sends theNCag_XXX Response message including the reject message to the AMF/SEAFindicating that the CAG cell is not allowed for the UE 104.

At step 1305, the AMF/SEAF 202 rejects the service request of the UE 104on receiving the reject message from the CAG server 110. At step 1306,the AMF/SEAF 202 sends the reject message and the appropriate causevalue to the UE 104.

FIG. 14 is a sequence diagram depicting verification of the permissionsof the UE to access the CAG cell at the UDM 206 on receiving the SUPI ofthe UE 104 from the AMF/SEAF, according to embodiments as disclosedherein. At step 1401, the UE 104 sends the service request to theAMF/SEAF 202 through the NG-RAN 106 a requesting the access for the CAGcell/NPN 102 b. In an embodiment, the UE 104 may also send the CAG ID ofthe requested CAG cell/NPN 102 b in the service request to the AMF/SEAF202 through the NG-RAN 106 a. In an embodiment, the NG-RAN 106 a maysend the CAG ID of the requested CAG cell/NPN 102 b along with theregistration request to the AMF/SEAF 202.

At step 1402, the AMF/SEAF 202 reveals the SUPI of the UE 104. TheAMF/SEAF 202 inserts the revealed SUPI of the UE 104, the CAG ID of therequested CAG cell/NPN 102 b in the Nudm_XXX Request message and sendsthe Nudm_XXX Request message to the UDM 206.

At step 1403, the UDM 206 retrieves the allowed list of CAG cells basedon the received SUPI. The UDM 206 verifies if the UE 104 has thepermissions to access the requested CAG cell/NPN 102 b based on theallowed list of CAG cells retrieved based on the SUPI of the UE 104, andthe CAG ID of the requested CAG cell. On verifying that the UE 104 haspermissions to the requested CAG cell, the UDM 206 inserts the acceptmessage, and the allowed list of CAG cells for the UE 104 in theNudm_XXX Response message. At step 1404, the UDM 206 sends the Nudm_XXXResponse message to the AMF/SEAF 202 indicating the successfulverification. At step 1405, the AMF/SEAF 202 may proceed further withthe registration request of the UE 104 on receiving the accept messagefrom the UDM 206.

On verifying that the UE 104 does not have the permissions to access theCAG cell/NPN 102 b, the UDM 206 inserts the reject message in theNudm_XXX Response message. At step 1404, the UDM 206 sends the Nudm_XXXResponse message including the reject message to the AMF/SEAF 202indicating that the CAG cell is not allowed for the UE 104. At step1405, the AMF/SEAF 202 rejects the registration request of the UE 104 onreceiving the reject message from the UDM 206. At step 1406, theAMF/SEAF 202 sends the reject message and the appropriate cause value tothe UE 104.

FIG. 15 is a flow diagram depicting a method 1500 for controlling thepermissions of the at least one UE 104 to access the at least one NPN102 b in wireless network 100, according to embodiments as disclosedherein. At step 1502, the method includes requesting, by the at leastone UE 104, the PLMN 102 a for accessing the at least one NPN 102 bthrough the at least one CAG cell.

At step 1504, the method includes verifying, by the CN 108 a of the PLMN102 a, the permissions of the at least one UE 104 for accessing therequested at least one NPN (102) through the at least one CAG cell.

At step 1506, the method includes performing, by the CN 108 a, theprimary authentication procedure to allow the at least one UE 104 foraccessing the at least one NPN 102 b through the at least one cell, ifthe permissions of the at least one UE 104 for accessing the requestedat least one NPN 102 through the at least one CAG cell is verified. Thevarious actions in method 1500 may be performed in the order presented,in a different order or simultaneously. Further, in some embodiments,some actions listed in FIG. 15 may be omitted.

According to various embodiments, a method for controlling permissionsof at least one User Equipment (UE) (104) to access at least oneNon-Public Network (NPN) (102 b) in a network (100), the methodcomprises requesting, by the at least one UE (104), a Public Land MobileNetwork (PLMN) (102 a) for accessing the at least one NPN (102 b)through at least one Closed Access Group (CAG) cell; verifying, by aCore Network (CN)(108a) of the PLMN (102 b), the permissions of the atleast one UE (104) for accessing the requested at least one NPN (102)through the at least one CAG cell; and performing, by the CN (108 a), aprimary authentication procedure to allow the at least one UE (104) foraccessing the at least one NPN (102 b) through the at least one CAGcell, if the permissions of the at least one UE (104) for accessing therequested at least one NPN (102) through the at least one CAG cell areverified.

In some embodiments, the at least one NPN (102 b) is deployed inconjunction with the PLMN (102 a) using the at least one CAG cell.

In some embodiments, the at least one NPN (102 b) includes at least oneof a non-standalone NPN (102 b), and a stand-alone NPN (102 b).

In some embodiments, at least one of a unified data management(UDM)(206), an access and mobility management function (AMF) (202), anauthentication server function (AUSF) 204 of the CN (108 a) verifies thepermissions of the at least one UE (104) to access the requested atleast one NPN (102) through the at least one CAG cell.

In some embodiments, a CAG server (110) coupled to the CN (108 a)verifies the permissions of the at least one UE (104) to access therequested at least one NPN (102).

In some embodiments, requesting, by the at least one UE (102), theaccess to the at least one NPN (102 a) includes: sending a requestincluding a subscription concealed identifier (SUCI) of the at least oneUE (102) to a Radio Access Network (RAN) (106 a) of the PLMN (102 b)).

In some embodiments, the method comprises: adding, by the RAN (106 a),at least one CAG Identifier (CAG ID) of the at least one NPN (102 b)that is requested by the at least one UE (104); and sending, by the RAN(106 b), the received SUCI of the UE (104) and the at least one CAG IDof the requested at least one NPN to the CN (108 a).

In some embodiments, requesting, by the at least one UE (102), theaccess to the at least one NPN (102 a) includes: sending the requestincluding the SUCI of the at least one UE (102) and the CAG ID of therequested at least one NPN to the RAN (106 a) of the PLMN (102 b).

In some embodiments, the CN (108 a) verifies the permissions of the atleast one UE (104) for accessing the at least one NPN (102 b), only ifthe received request message includes the at least one CAG ID.

In some embodiments, verifying, by the CN (108 a), the permissions ofthe at least one UE (104) includes: receiving the SUCI of the at leastone UE (104), and the at least one CAG ID of the requested at least oneNPN (102 a) from the RAN (106 a); deriving an allowed list of CAG cellsfor the at least one UE (104) based on the received SUCI of the at leastone UE (104); and verifying the permissions of the at least one UE (104)to access the requested at least one NPN (102 b) using the derivedallowed list of CAG cells and the received at least one CAG ID of therequested at least one NPN (102 b).

In some embodiments, deriving the allowed list of CAG cells for the atleast one UE (104) includes: revealing the received SUCI of the at leastone UE (104) to a subscription permanent identifier (SUPI); mapping therevealed SUPI of the at least one UE (104) with a map of the allowedlist of CAG cells and the SUPIs of a plurality of UEs; and deriving theallowed list of CAG cells for the at least one UE (104) if theassociated SUPI maps with the revealed SUPI of the at least one UE(104).

In some embodiments, verifying the permissions of the at least one UE(104) using the derived allowed list of CAG cells and the received CAGID of the requested at least one NPN (102 b) includes: determining ifthe received at least one CAG ID of the requested at least one NPN (102b) is present in the derived allowed list of CAG cells; verifying thatthe at least one UE (104) has the permissions for accessing therequested at least one NPN (102 b) if the at least one received CAG IDof the requested at least one NPN (102 b) is present in the derivedallowed list of CAG cells; and verifying that the at least one UE (104)does not have the permissions for accessing the requested at least oneNPN (102 b) if the received at least one CAG ID of the requested atleast one NPN (102 b) is not present in the derived allowed list of CAGcells.

In some embodiments, the method comprises rejecting the request of theat least one UE (104) on verifying that the at least one UE (104) doesnot have the permissions for accessing the requested at least one NPN(102 b); and sending a reject message to the at least one UE (104) witha cause value, wherein the cause value indicating at least one cause ofan error for rejecting the request of the at least one UE (104).

In some embodiments, performing the primary authentication procedureincludes: generating an authentication vector based on the revealed SUPIof the at least one UE (104) on verifying that the at least one UE (104)has the permissions for accessing the requested at least one NPN (102b); authenticating the at least one UE (104) based on the generatedauthentication vector on determining that if the at least one UE (104)has NPN permissions to access the requested at least one NPN (102 b)through the PLMN (102 a): and enabling the at least one UE (104) toaccess the at least one requested NPN (102 b) if the at least one UE(104) has the NPN permissions to access the requested at least one NPN(102 b) through the PLMN (102 a).

According to various embodiments, a network (100) comprises at least oneUser Equipment (UE) (104); at least one Non-Public network (NPN) (102a); and a Public Land Mobile Network (PLMN) (102 a). The at least oneNPN (102 b) is deployed in conjunction with the PLMN (102 a), whereinthe PLMN (102 a) includes at least one cellular network (102 a)comprising of a Radio Access Network (106 a) and a Core Network (CN)(108 a). The at least one UE (104) is configured to: request the PLMN(102 a) for accessing the at least one NPN (102 a) through at least oneClosed Access Group (CAG) cell. The CN (108 a) is configured to verifypermissions of the at least one UE (104) for accessing the requested atleast one NPN (102) via the at least one CAG cell; and perform a primaryauthentication procedure to allow the at least one UE (104) foraccessing the at least one NPN (102 b) through the at least one CAGcell, if the permissions of the at least one UE (104) for accessing therequested at least one NPN (102) through the at least one CAG cell areverified.

In some embodiments, the at least one NPN (102 b) is deployed inconjunction with the PLMN (102 a) using the at least one CAG cell.

In some embodiments, the at least one NPN (102 b) includes at least oneof a non-standalone NPN (102 b), and a stand-alone NPN (102 b).

In some embodiments, at least one of a unified data management (UDM)(206), an access and mobility management function (AMF) (202), anauthentication server function (AUSF) 204 of the CN (108 a) is furtherconfigured to verify the permissions of the at least one UE (104) toaccess the requested at least one NPN (102) through the at least one CAGcell.

In some embodiments, the PLMN (102 a) further comprises a CAG server(110) coupled with the CN (108 a) configured to verify the permissionsof the at least one UE (104) to access the requested at least one NPN(102).

In some embodiments, the at least one UE (102) is further configured tosend a request including a subscription concealed identifier (SUCI) ofthe at least one UE (102) to the RAN (106 a) of the PLMN (102 b)requesting access to the at least one NPN (102 b).

In some embodiments, the at least one RAN (106 a) is further configuredto: add at least one CAG identifier (CAG ID) of the at least one NPN(102 b) that is requested by the at least one UE (104); and send thereceived SUCI of the UE (104) and the CAG ID of the requested at leastone NPN to the CN (108 a).

In some embodiments, the at least one UE (102) is further configured tosend the request including the SUCI of the at least one UE (102) and theCAG ID of the requested at least one NPN to the RAN (106 a) of the PLMN(102 b).

In some embodiments, the CN (108 a) is further configured to verify thepermissions of the at least one UE (104) for accessing the at least oneNPN (102 b), only if the received request messages includes the at leastone CAG ID.

In some embodiments, the CN (108 a) is further configured to: receivethe SUCI of the at least one UE (104), and the at least one CAG ID ofthe requested at least one NPN (102 a) from the RAN (106 a); derive anallowed list of CAG cells for the at least one UE (104) based on thereceived SUCI of the at least one UE (104); and verify the permissionsof the at least one UE (104) to access the requested at least one NPN(102 b) using the derived allowed list of CAG cells and the received atleast one CAG ID of the requested at least one NPN (102 b).

In some embodiments, the CN (108 a) is further configured to: reveal thereceived SUCI of the at least one UE (104) to a subscription permanentidentifier (SUPI); map the revealed SUPI of the at least one UE (104)with a map of the allowed list of CAG cells and the SUPIs of a pluralityof UEs; and derive the allowed list of CAG cells for the at least one UE(104) if the associated SUPI maps with the revealed SUPI of the at leastone UE (104).

In some embodiments, the CN (108 a) is further configured to: determineif the received at least one CAG ID of the requested at least one NPN(102 b) is present in the derived allowed list of CAG cells; verify thatthe at least one UE (104) has the permissions for accessing therequested at least one NPN (102 b) if the received at least one CAG IDof the requested at least one NPN (102 b) is present in the derivedallowed list of CAG cells; and verify that the at least one UE (104)does not have the permissions for accessing the requested at least oneCAG cell of the at least one NPN (102 b) if the received CAG ID of therequested at least one NPN (102 b) is not present in the derived allowedlist of CAG cells.

In some embodiments, the CN (108 a) is further configured to: reject therequest of the at least one UE (104) on verifying that the at least oneUE (104) does not have the permissions for accessing the requested atleast one CAG ID of the at least one NPN (102 b); and send a rejectmessage to the at least one UE (104) with a cause value, wherein thecause value indicating at least one cause of an error for rejecting therequest of the at least one UE (104).

In some embodiments, the CN (108 a) is further configured to: generatean authentication vector based on the received SUPI of the at least oneUE (104) on verifying that the at least one UE (104) has the permissionsfor accessing the requested at least one NPN (102 b); authenticate theat least one UE (104) based on the generated authentication vector ondetermining that if the at least one UE (104) has NPN permissions toaccess the requested at least one NPN (102 b) through the PLMN (102 a):and enable the at least one UE (104) to access the at least onerequested NPN (102 b) if the at least one UE (104) has the NPNpermissions to access the requested at least one NPN (102 b) through thePLMN (102 a).

According to various embodiments, a network (100) comprises at least oneUser Equipment (UE) (104); at least one Non-Public Network (NPN) (102a); and a Public Land Mobile Network (PLMN) (102 a), wherein the atleast one NPN (102 b) is deployed in conjunction with the PLMN (102 a)through at least one Closed Access Group (CAG) cell, wherein the PLMN(102 a) includes at least one cellular network (102 a) comprising of aRadio Access Network (106 a) and a Core Network (CN) (108 a). The atleast one UE (104) is configured to request the PLMN (102 a) for anaccess to the at least one NPN (102 a). The CN (108 a) comprises aunified data management (UDM) (206) configured to: verify permissions ofthe at least one UE (104) to access the requested at least one NPN(102); and initiate a primary authentication procedure, if thepermissions of the at least one UE (104) to access the requested atleast one NPN (102) are verified.

In some embodiments, the at least one UE (104) is further configured to:send a request including a subscription concealed identifier (SUCI) ofthe at least one UE (104) to the RAN (106 a) of the PLMN (102 b)requesting access to the at least one NPN (102 b); wherein the RAN (106a) is configured to: add a CAG ID of the at least one NPN (102 b) thatis requested by the at least one UE (104); and send the received SUCI ofthe UE (104) and the CAG ID of the requested at least one NPN (102 a) tothe CN (108 a).

In some embodiments, the at least one UE (104) is further configured tosend the request including the SUCI of the at least one UE (102) and theCAG ID of the requested at least one NPN to the RAN (106 a) of the PLMN(102 b).

In some embodiments, the CN (108 a) further comprises: an access andmobility management function (AMF) (202) and an authentication serverfunction (AUSF) 204; wherein the AMF (202) is configured to: receive theSUCI of the at least one UE (104) and the CAG ID of the requested atleast one NPN (102 a) from the RAN (106 a); insert the received SUCI ofthe at least one UE (104) and the CAG ID of the requested at least oneNPN (102 a) in an authentication request message(Nusf_UEAuthentication_Authenticate Request message); and send theauthentication request message to the AUSF (204). The AUSF (204) isfurther configured to derive the SUCI of the at least one UE (104) andthe CAG ID of the requested at least one NPN (102 a) from the receivedauthentication request message; insert the derived SUCI of the at leastone UE (104) and the CAG ID of the requested at least one NPN (102 a) inan authentication get request message (Nudm_UEAuthentication_Get_Requestmessage; and sending the authentication get request message to the UDM(206).

In some embodiments, the UDM (206) is further configured to: receive theSUCI of the at least one UE (104), and the CAG ID of the requested atleast one NPN (102 a) from the AUSF (204); reveal the received SUCI ofthe at least one UE (104) to a subscription permanent identifier (SUPI);map the revealed SUPI of the at least one UE (104) with a map of theallowed list of CAG cells and the SUPIs of a plurality of UEs; retrievethe allowed list of CAG cells for the at least one UE (104) if theassociated SUPI maps with the revealed SUPI of the at least one UE(104); verify that the at least one UE (104) has the permissions toaccess the requested at least one NPN (102 b) if the received CAG ID ofthe requested at least one NPN (102 b) is present in the retrievedallowed list of CAG cells; and verify that the at least one UE (104)does not have the permissions to access the requested at least one NPN(102 b) if the received CAG ID of the requested at least one NPN (102 b)is not present in the retrieved allowed list of CAG cells.

In some embodiments, the UDM (206) is further configured to: insert areject message and the SUPI of the at least one UE (204) in anauthentication get request message (Nudm_UEAuthentication_Get Responsemessage) on verifying that the at least one UE (104) does not have theaccess to the requested at least one NPN (102 b); send theauthentication get response message to the AUSF (204). The AUSF (204) isfurther configured to: derive the reject message from the receivedauthentication get response message and insert the derived rejectmessage in an authentication response message(Nausf_UEAuthentication_Authenticate Response message); send theauthentication response message to the AMF (202). The AMF (202) isfurther configured to: reject the request of the at least one UE (104)on receiving the reject message from the AUSF (204); and send a rejectmessage to the at least one UE (104) through the RAN (106 a) with acause value, wherein the cause value indicating at least one cause of anerror for rejecting the request of the at least one UE (104).

In some embodiments, the UDM (206) is further configured to: generate anauthentication vector based on the received SUCI of the at least one UE(104) on verifying the at least one UE (104) has the permissions toaccess the requested at least one NPN (102 b); send the authenticationvector to the AMF (202) through the AUSF (204); the AMF (202) is furtherconfigured to: authenticate the at least one UE (104) based on thereceived authentication vector to determine if the at least one UE (104)has NPN permissions to access the requested at least one NPN (102 b)through the PLMN (102 a); and enable the at least one UE (104) to accessthe at least one requested NPN (102 b) if the at least one UE (104) hasthe NPN permissions to access the requested at least one NPN (102 b)through the PLMN (102 a).

According to various embodiments, a core network CN (108 a) of a PublicLand Mobile Network (PLMN) (102 a), wherein the PLMN (102 a) is inconjunction with at least one non-public network (NPN) (102 a) andconnected to at least one User Equipment (UE) (104), wherein the CN (108a) is configured to: receive a request from the at least one UE (104)through a Radio Access Network (RAN) (106 a) for access to the at leastone NPN (102 a); verify permissions of the at least one UE (104) toaccess the requested at least one NPN (102); and perform a primaryauthentication procedure, if the permissions of the at least one UE(104) to access the requested at least one NPN (102) are verified.

In some embodiments, the request of the at least one UE (104 includes asubscription concealed identifier (SUCI) of the at least one UE (102)and a Closed Access Group (CAG ID) of the at least one NPN (102 b) thatis requested by the at least one UE (104).

In some embodiments, the CN (108 a) is further configured to: reveal thereceived SUCI of the at least one UE (104) to a subscription permanentidentifier (SUPI); map the revealed SUPI of the at least one UE (104)with a map of the allowed list of CAG cells and the SUPIs of a pluralityof UEs; retrieve the allowed list of CAG cells for the at least one UE(104) if the associated SUPI maps with the revealed SUPI of the at leastone UE (104); verify that the at least one UE (104) has the permissionsto access the requested at least one NPN (102 b) if the received CAG IDof the requested at least one NPN (102 b) is present in the retrievedallowed list of CAG cells; and verify that the at least one UE (104)does not have the permissions to access the requested at least one NPN(102 b) if the received CAG ID of the requested at least one NPN (102 b)is not present in the retrieved allowed list of CAG cells.

In some embodiments, the CN (108 a) is further configured to: reject therequest of the at least one UE (104) on verifying that the at least oneUE (104) does not have the permissions to access the requested at leastone NPN (102 b); and send a reject message to the at least one UE (104)through the RAN (106 a) with a cause value, wherein the cause valueindicating at least one cause of an error for rejecting the request ofthe at least one UE (104).

The embodiments disclosed herein can be implemented through at least onesoftware program running on at least one hardware device and performingnetwork management functions to control the elements. The elements shownin FIGS. 1A-14 can be at least one of a hardware device, or acombination of hardware device and software module.

The embodiments disclosed herein describe methods and systems formitigating Denial of Service (DoS) attack in a wireless network.Therefore, it is understood that the scope of the protection is extendedto such a program and in addition to a computer readable means having amessage therein, such computer readable storage means contain programcode means for implementation of one or more steps of the method, whenthe program runs on a server or mobile device or any suitableprogrammable device. The method is implemented in an embodiment throughor together with a software program written in e.g. Very high speedintegrated circuit Hardware Description Language (VHDL) anotherprogramming language, or implemented by one or more VHDL or severalsoftware modules being executed on at least one hardware device. Thehardware device can be any kind of portable device that can beprogrammed. The device may also include means which could be e.g.hardware means like e.g. an ASIC, or a combination of hardware andsoftware means, e.g. an ASIC and an FPGA, or at least one microprocessorand at least one memory with software modules located therein. Themethod embodiments described herein could be implemented partly inhardware and partly in software. Alternatively, the present disclosuremay be implemented on different hardware devices, e.g. using a pluralityof CPUs.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of embodiments, those skilled in theart will recognize that the embodiments herein can be practiced withmodification within the scope of the embodiments as described herein.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a security anchor function(SEAF), the method comprising: receiving, from a user equipment (UE) viaa base station, a registration request message including a subscriptionconcealed identifier (SUCI) of the UE; receiving, from the base station,a closed access group (CAG) identifier of a CAG cell via an access andmobility function (AMF); transmitting, to a unified data management(UDM) via an authentication server function (AUSF), a request messageincluding: the SUCI of the UE, and the CAG identifier of the CAG cell;in case that the UE is not allowed to access the CAG Cell, receiving,from the UDM via the AUSF, a reject message for indicating a rejectionof the CAG Cell; and in case that the UE is allowed to access the CAGCell, performing an authentication procedure of the UE.
 2. The method ofclaim 1, wherein the SUCI is used to obtain a subscription permanentidentifier (SUPI) of the UE for verifying if the UE is allowed to accessthe CAG cell or not in the UDM.
 3. The method of claim 1, wherein theauthentication procedure is performed by using an authentication vectorgenerated by the UDM.
 4. The method of claim 1, wherein anauthentication method for the authentication procedure is selected bythe UDM.
 5. The method of claim 1, wherein the request message furtherincludes a serving network (SN) name.
 6. A method performed by a userequipment (UE), the method comprising: transmitting, to a securityanchor function (SEAF) entity via a base station, a registration requestto access a closed access group (CAG) Cell, the registration requestincludes a subscription concealed identifier (SUCI) of the UE; in casethat the UE is not allowed to access the CAG Cell, receiving, from theSEAF entity, a reject message for indicating a rejection of the CAGCell; and in case that the UE is allowed to access the CAG Cell,performing an authentication procedure between a network and the UE, theauthentication procedure using an authentication vector.
 7. The methodof claim 6, wherein the SUCI is used to obtain a subscription permanentidentifier (SUPI) of the UE for verifying if the UE is allowed to accessthe CAG cell or not in unified data management (UDM).
 8. The method ofclaim 6, wherein the authentication procedure is performed by using anauthentication vector generated by a UDM.
 9. The method of claim 6,wherein an authentication method for the authentication procedure isselected by a UDM.
 10. The method of claim 6, wherein the SEAF isassociated with an access and mobility function (AMF).
 11. An apparatusof a security anchor function (SEAF), comprising: at least onetransceiver; and at least one processor operably coupled to the at leastone transceiver, configured to: receive, from a user equipment (UE) viaa base station, a registration request message including a subscriptionconcealed identifier (SUCI) of the UE; receive, from the base station, aclosed access group (CAG) identifier of a CAG cell via an access andmobility function (AMF); transmit, to a unified data management (UDM)via an authentication server function (AUSF), a request messageincluding: the SUCI of the UE, and the CAG identifier of the CAG cell;in case that the UE is not allowed to access the CAG Cell, receive, fromthe UDM via the AUSF, a reject message for indicating a rejection of theCAG Cell; and in case that the UE is allowed to access the CAG Cell,perform an authentication procedure of the UE.
 12. The apparatus ofclaim 11, wherein the SUCI is used to obtain a subscription permanentidentifier (SUPI) of the UE for verifying if the UE is allowed to accessthe CAG cell or not in the UDM.
 13. The apparatus of claim 11, whereinthe authentication procedure is performed by using an authenticationvector generated by the UDM.
 14. The apparatus of claim 11, wherein anauthentication method for the authentication procedure is selected bythe UDM.
 15. The apparatus of claim 11, wherein the request messagefurther includes a serving network (SN) name.
 16. A user equipment (UE),comprising: at least one transceiver; and at least one processoroperably coupled to the at least one transceiver, configured to:transmit, to a security anchor function (SEAF) entity via a basestation, a registration request to access a closed access group (CAG)Cell, the registration request includes a subscription concealedidentifier (SUCI) of the UE; in case that the UE is not allowed toaccess the CAG Cell, receive, from the SEAF entity, a reject message forindicating a rejection of the CAG Cell; and in case that the UE isallowed to access the CAG Cell, perform an authentication procedurebetween a network and the UE, the authentication procedure using anauthentication vector.
 17. The UE of claim 16, wherein the SUCI is usedto obtain a subscription permanent identifier (SUPI) of the UE forverifying if the UE is allowed to access the CAG cell or not in aunified data management (UDM).
 18. The UE of claim 16, wherein theauthentication procedure is performed by using an authentication vectorgenerated by a UDM.
 19. The UE of claim 16, wherein an authenticationmethod for the authentication procedure is selected by a UDM.
 20. The UEof claim 16, wherein the SEAF is associated with an access and mobilityfunction (AMF).